As filed with the Securities and Exchange Commission on January 20, 2004
                          Registration No. ___________


                       SECURITIES AND EXCHANGE COMMISSION
                              Washington, DC 20549
                    ----------------------------------------

                                    FORM S-3
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933
                    ----------------------------------------

                              Ionics, Incorporated
             (Exact name of Registrant as specified in its charter)
                          -----------------------------

                   Massachusetts                              04-2068530
           (State or other jurisdiction                     (I.R.S. Employer
         of incorporation or organization)               Identification Number)

                                 65 Grove Street
                            Watertown, MA 02472-2882
                                 (617) 926-2500
               (Address, including zip code, and telephone number,
        including area code, of Registrant's principal executive offices)
                    ----------------------------------------

                                Douglas R. Brown
                      President and Chief Executive Officer
                              Ionics, Incorporated
                                 65 Grove Street
                            Watertown, MA 02472-2882
                                 (617) 926-2500
            (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)
                    ----------------------------------------

  Copies of all communications, including all communications sent to the agent
                        for service, should be sent to:

         Stephen Korn, Esq.                      Mark H. Burnett, Esq.
 Vice President and General Counsel         Testa, Hurwitz & Thibeault, LLP
        Ionics, Incorporated                        125 High Street
           65 Grove Street                    Boston, Massachusetts 02110
      Watertown, MA 02472-2882                      (617) 248-7000
         (617) 673-4450

Approximate date of commencement of proposed sale to the public: From time to
     time after this Registration Statement becomes effective. If the only
     securities being registered on this form are being offered pursuant to
     dividend or interest reinvestment plans, please check
the following box.
    If any of the securities being registered on this Form are to be offered on
a delayed or continuous basis pursuant to Rule 415 under the Securities Act of
1933, other than securities offered only in connection with dividend or
interest reinvestment plans, check the following box.
     If this Form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following
box and list the Securities Act registration statement number of the earlier
effective registration statement for the same offering.
     If this Form is a post-effective amendment filed pursuant to Rule 462(c)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering.
     If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following.



                         CALCULATION OF REGISTRATION FEE
------------------------------------------------- --------------- ------------------------- -------------------------- -------------
                                                   Amount to be       Proposed Maximum          Proposed Maximum          Amount of
        Title of Shares to be Registered          Registered(1)      Offering Price Per        Aggregate Offering       Registration
                                                                          Share(2)                  Price(2)               Fee(2)
------------------------------------------------- --------------- ------------------------- -------------------------- -------------
                                                                                                           
Common Stock, $1.00 par value per share (and        4,905,660              $30.12
associated common stock purchase rights) (2)                                                $147,758,479               $11,953.62
------------------------------------------------- --------------- ------------------------- -------------------------- -------------


(1) The number of shares of Ionics common stock being registered hereunder
represents the maximum aggregate number of shares of Ionics common stock
issuable to the selling stockholders pursuant to the purchase agreement dated as
of November 18, 2003, by and among Ionics, Incorporated and the owners of
Ecolochem Inc., and its affiliated companies. The final apportionment of such
shares among the selling stockholders has not yet been determined. The actual
number of shares issued to the selling stockholders will be set forth in a final
prospectus filed pursuant to Rule 424(b). Pursuant to Rule 416 under the


Securities Act of 1933, as amended, this prospectus will also cover an
indeterminable number of additional shares of common stock that may be issued to
prevent dilution resulting from stock splits, stock dividends or similar
transactions affecting the shares to be offered by the selling stockholders. (2)
Estimated solely for the purpose of calculating the registration fee pursuant to
Rule 457 under the Securities Act of 1933. Pursuant to Rule 457(c) under the
Securities Act of 1933, the registration fee has been calculated based upon the
average of the high and low prices per share of the common stock of Ionics,
Incorporated on the New York Stock Exchange on January 16, 2004. The common
stock purchase rights that accompany the common stock are issued without further
consideration.

         The Registrant hereby amends this registration statement on such date
or dates as may be necessary to delay its effective date until the Registrant
shall file a further amendment which specifically states that this registration
statement shall thereafter become effective in accordance with Section 8(a) of
the Securities Act of 1933 or until the registration statement shall become
effective on such date as the Commission, acting pursuant to Section 8(a), may
determine.
===============================================================================




                              EXPLANATORY STATEMENT

        Ionics, Incorporated and the owners of the outstanding equity interests
of Ecolochem, Inc., Ecolochem International, Inc., Moson Holdings, LLC, and
Ecolochem S.A.R.L. (collectively, the "Ecolochem Group") have entered into the
Purchase Agreement (referred to in this registration statement as the "purchase
agreement") dated as of November 18, 2003, pursuant to which Ionics will acquire
the Ecolochem Group.

         The 4,905,660 shares registered for resale pursuant to this
registration statement and the prospectus included in this registration
statement represent the maximum aggregate number of shares of Ionics common
stock to be issued in connection with the acquisition. The final determination
of the number of shares of Ionics common stock to be apportioned among the
stockholders of Ecolochem, Inc. and Ecolochem International, Inc. will be
determined at the closing of Ionics' acquisition of the Ecolochem Group. The
actual number of shares issued to the selling stockholders will be set forth in
a final prospectus filed pursuant to Rule 424(b).

         Certain statements in the prospectus included in this registration
statement assume completion of the acquisition of the Ecolochem Group by Ionics.
There can be no assurance, however, that the acquisition will be completed, or
if it is completed, when the closing of the acquisition will occur.






                 Subject to completion, dated January 20, 2004.

THE INFORMATION IN THIS PROSPECTUS IS NOT COMPLETE AND MAY BE CHANGED. THE
SECURITIES REGISTERED HEREUNDER MAY NOT BE SOLD UNTIL THE REGISTRATION STATEMENT
FILED WITH THE SECURITIES AND EXCHANGE COMMISSION IS EFFECTIVE. THIS PROSPECTUS
IS NOT AN OFFER TO SELL SECURITIES, AND IT IS NOT SOLICITING OFFERS TO BUY THESE
SECURITIES IN ANY STATE WHERE THE OFFER OR SALE IS NOT PERMITTED.

                                   PROSPECTUS

                              IONICS, Incorporated

                                4,905,660 Shares

                                  Common Stock

         This prospectus relates to 4,905,660 shares of our common stock held by
the selling stockholders. We will not receive any proceeds from the sale of
these shares by the selling stockholders. We have agreed to bear substantially
all of the expenses in connection with the registration and resale of the shares
(other than selling commissions and fees).

         The selling stockholders include Lyman B. Dickerson; Douglas G.
Dickerson; The Estate of Richard C. Dickerson; The Lyman B. Dickerson Revocable
Trust Dated September 9, 1996 or any Successor Trustee, as amended; The Richard
Dickerson Revocable Trust Dated March 5, 1993, or any Successor Trustee, as
amended; The Douglas G. Dickerson Revocable Trust Dated June 22, 1988, or any
Successor Trustee, as amended; The Lyman Dickerson Irrevocable Trust, dated July
1, 2001; The Richard Dickerson Irrevocable Trust No. 3, dated July 1, 1991; and
The Douglas Dickerson Irrevocable Trust No. 3, dated July 1, 1991 and certain of
their permitted transferees. The selling stockholders will acquire the offered
shares directly from Ionics upon the consummation of Ionics' acquisition of
Ecolochem, Inc. and its affiliated companies. The selling stockholders, or their
permitted transferees or other successors-in-interest, may offer the shares from
time to time through public or private transactions at prevailing market prices,
at prices related to prevailing market prices or at privately negotiated prices.

         Our common stock is traded on the New York Stock Exchange under the
symbol "ION." On January 16, 2004, the closing sale price of our common stock on
the New York Stock Exchange was $30.08 per share.
                            ------------------------

                  Investing in our common stock involves risk.
                     See "Risk Factors" beginning on page 1.
                            ------------------------

         Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities, or determined if
this prospectus is truthful or complete. Any representation to the contrary is a
criminal offense.

         Prospective investors should rely only on the information contained in
this prospectus or information specifically incorporated by reference in this
prospectus. We have not authorized anyone to provide prospective investors with
information that is different.

         Neither the delivery of this prospectus, nor any sale of the shares,
shall create any implication that the information in this prospectus is correct
after the date hereof.


                The date of this prospectus is ________ __, 2004.





                            ------------------------

                                TABLE OF CONTENTS
                                                                         Page
Ionics, Incorporated..............................................        1
Risk Factors......................................................        1
Special Note Regarding Forward-Looking Information................       10
Use of Proceeds...................................................       11
Selling Stockholders..............................................       11
Plan of Distribution..............................................       13
Legal Matters.....................................................       15
Experts...........................................................       15
Where You Can Find More Information...............................       16
Incorporation of Certain Documents by Reference...................       16
                            ------------------------






                              IONICS, INCORPORATED

         We are a leading water purification company engaged worldwide in the
supply of water and related activities and the supply of water treatment
equipment through the use of proprietary separations technologies and systems.
Our products and services are used by us or our customers to desalt brackish
water and seawater, recycle and reclaim process water and wastewater, treat
water in the home, manufacture and supply water treatment chemicals and
ultrapure water, process food products and recycle and measure levels of
waterborne contaminants and pollutants. Our customers include industrial
companies, consumers, municipalities and other governmental entities, and
utilities.

         Ionics was incorporated in Massachusetts in 1948. Our principal
executive offices are located at 65 Grove Street, Watertown, Massachusetts 02472
and our telephone number is (617) 926-2500.

                                  RISK FACTORS

     You should  carefully  consider the risks described below before you decide
to buy our common stock. The risks and uncertainties described below are not the
only ones facing our company. Additional risks and uncertainties may also impair
our business operations. In evaluating our business and before you decide to buy
our common stock, you should consider carefully the following risks, in addition
to the other  information  contained in this  prospectus and the other documents
incorporated  by reference into this  prospectus.  If any of the following risks
actually occur, our business, financial condition or results of operations would
likely  suffer.  In such  case,  the  trading  price of our common  stock  could
decline,  and you may lose all or part of the money  you paid to buy our  common
stock.

Our results of operations may fluctuate significantly on a quarterly basis.

         Our quarterly operating results may vary significantly from quarter to
quarter, depending on a number of factors including:

o the introduction and market acceptance of new products and new variations of
  existing products;
o the activities of competitors;
o our ability to control expenses;
o variations in the timing of orders and subsequent shipments;
o length of approval processes or market tests;
o changes in our mix of products;
o disruption in our sources of supply;
o personnel changes;
o changes in our capital spending;
o unforeseeable or unavoidable delays in large-scale customer projects;
o higher interest rates; and
o general economic conditions.

The market value of the shares of our common stock issuable in connection with
the acquisition of the Ecolochem Group may increase prior to the closing of the
acquisition and, therefore, we may be perceived to have paid more for the
Ecolochem Group.

         The number of shares of our common stock issuable pursuant to the
acquisition was fixed at the time of the signing of the purchase agreement with
the owners of the Ecolochem Group and is not subject to adjustment based on
changes in the trading price of our common stock before the closing of the
acquisition. Therefore, the market value of the shares of our common stock


issued in connection with the acquisition will likely fluctuate through the
closing of the acquisition and thereafter. As a result, the value of the
acquisition, as reflected in the relative market price of our common stock, may
vary significantly from the date of execution of the purchase agreement and the
date the acquisition is completed. This variance may arise due to, among other
things: changes in our business, operations and prospects; market assessments of
the likelihood that the acquisition will be completed; demand for water
processing in our markets; and interest rates, general market and economic
conditions and other factors. Substantially all of these factors are beyond our
control. As a result of increases in the market price of our common stock,
financial or industry analysts or others may perceive that we paid more for the
Ecolochem Group than they believe was prudent. If this perception materializes,
the trading price of our common stock could be adversely affected.

The  anticipated  benefits  of  acquiring  Ecolochem,  Inc.  and its  affiliated
companies (the "Ecolochem Group") may not be realized.

         We agreed to acquire the Ecolochem Group with the expectation that the
acquisition would result in various benefits including, among other things,
enhanced revenue, profits, market presence, cost savings and operating
efficiencies. We expect that the acquisition will enhance our position in the
water treatment services market through the combination of our technologies,
products, services and customer contacts with those of the Ecolochem Group, and
will enable us to broaden our customer base in the electric power and
petrochemical industries. If our business or the Ecolochem Group's business
fails to meet the demands of the marketplace, customer acceptance of our
products and services could decline, which would have an adverse effect on our
results of operations and financial condition. We may not realize any of these
benefits and the acquisition may result in the deterioration or loss of
significant business. Costs incurred and potential liabilities assumed in
connection with the acquisition, including pending and threatened disputes,
litigation and environmental liabilities, could have a material adverse effect
on our business, financial condition and operating results.

         In addition, we may not achieve the anticipated benefits as rapidly as,
or to the extent, anticipated by certain financial or industry analysts, or
other analysts may not perceive the same benefits to the acquisition as we do.
If these risks materialize, our stock price could be adversely affected.

Our restructuring program may not result in the intended financial performance
improvements.

     On September  3, 2003,  we announced a  restructuring  program  intended to
improve  our  financial  performance  through a  realignment  of our  management
structure,   a  reduction  in  personnel,   and  the  consolidation  of  certain
operations.  The program when fully carried out would result in the  elimination
of approximately 200 positions,  or approximately  10% of our workforce,  and is
anticipated  to result in annual  personnel  cost savings of  approximately  $14
million and annual  facilities cost savings of  approximately  $1.4 million.  In
connection with the restructuring  program, we anticipate  incurring charges for
severance costs, facilities shutdown and relocation costs, and reporting process
improvement  costs  totaling  approximately  $11  million,  as well as  goodwill
impairment and other long-lived asset impairment charges.

         A number of the planned restructuring actions have been taken, and
others have yet to be implemented. We may not be able to complete the
implementation of the restructuring program to the extent and according to the
timetable presently expected. The cost savings we realize from the restructuring
may be less than anticipated, and the overall restructuring charges we incur may
be greater than anticipated. Consequently, the overall impact of the
restructuring on our profitability may differ from our original estimate.

We may have difficulty and incur substantial costs integrating the Ecolochem
Group.


                                      -2-



         Integrating the Ecolochem Group will be a complex, time-consuming and
expensive process. Before the acquisition of Ecolochem Group, Ionics and the
Ecolochem Group operated independently, each with its own business, products,
customers, employees, culture and systems, including data management and
financial systems. Additionally, we are currently in the process of
restructuring our business and operations. We may face substantial difficulties,
costs and delays in integrating the Ecolochem Group, which may include:

o    perceived  adverse  changes in product or  service  offerings  or  customer
     service standards, whether or not these changes do, in fact, occur;

o    costs and delays in implementing  common  information and other systems and
     procedures  and costs and delays caused by  communication  difficulties;

o    potential  difficulty in applying our accounting controls and procedures to
     the members of the  Ecolochem  Group,  which have  operated as  independent
     private companies;

o    charges to earnings  resulting from the application of purchase  accounting
     to the  acquisition;

o    diversion of management resources;

o    potential incompatibility of business cultures;

o    potential  losses of  management  and other key  employees due to perceived
     uncertainty in career  opportunities,  compensation levels and benefits;

o    the retention of existing customers of each company;

o    reduction  or loss of  customer  orders  due to the  potential  for  market
     confusion,   hesitation  and  delay;  and

o    coordinating infrastructure operations in a rapid and efficient manner.

         After the acquisition, we will seek to combine certain operations and
functions using common information and communication systems, operating
procedures, financial controls and human resource practices, including training,
professional development and benefit programs. We may be unsuccessful, or
experience delays, in implementing the integration of these systems and
processes.

         Any one or all of these factors may cause increased operating costs,
worse than anticipated financial performance or the loss of customers and
employees. Many of these factors are outside our control. The failure to timely
and efficiently integrate the Ecolochem Group could have a material adverse
effect on our business, financial condition and operating results. In addition,
the differences between the business cultures could present significant
obstacles to timely, cost-effective integration of the Ecolochem Group.

We may have difficulty establishing appropriate controls and procedures on a
timely basis with respect to the Ecolochem Group's financial reporting as our
subsidiaries.

         We have been implementing a number of measures and procedures to ensure
that our disclosure controls and procedures and internal controls over financial
reporting are effective. The acquisition of the Ecolochem Group will add
significant business units to our operations, which, prior to the acquisition,
were operated as private businesses and were not subject to the various
reporting obligations imposed on publicly traded companies. We will be required
to establish appropriate controls and procedures in accordance with our policies
and procedures with respect to the Ecolochem Group's financial reporting.
Failure to establish those controls and procedures in a timely manner, or any
failure of those controls and procedures once established, could adversely
impact our public disclosures regarding our business, financial condition or
operating results, which may adversely impact the price of our common stock.

The debt we will incur in connection with the acquisition of the Ecolochem Group
will create financial and operating risks that could limit our operating
flexibility and growth.


                                      -3-


         As a result of the acquisition of the Ecolochem Group, we will incur
substantial additional debt. We expect that the terms of the new credit
facilities will contain provisions that limit our ability to incur additional
indebtedness in the future and place other restrictions on our business. We may
not be able to repay any current or future debt on a timely basis, depending on
our future operating results. We will be required to devote increased amounts of
our cash flow to service indebtedness incurred in connection with the
acquisition or incurred in the future. This could require us to modify, delay or
abandon our capital expenditures and other investments necessary to implement
our business plan.

         A portion of this debt, as well as other short-term and long-term
borrowings, will be subject to variable interest rates tied to prime rates or
other indices. We will be subject to the risk that interest rates may increase
significantly and increase the cost of our debt.

The success of our strategic plan to grow sales and develop relationships
internationally may be limited by risks related to conducting business in
international markets.

    Although both Ionics and the Ecolochem Group have experience marketing and
distributing their products and services and developing strategic relations in
Europe and other foreign markets, part of our strategy will be to increase sales
and build additional relationships in Europe and other foreign markets. Risks
inherent in marketing, selling and developing relationships in European and
other foreign markets include those associated with:

o    Economic  conditions  in  those  markets,  including  fluctuations  in  the
     relative values of the U.S. dollar and foreign  currencies;
o    Taxes and fees imposed by foreign governments that may increase the cost of
     products and services; and
o    Laws and regulations imposed by individual countries and by the European
     Union and other governmental bodies.

We have only limited protection for our proprietary technology.

         We rely on a combination of patent, trademark and trade secret laws and
restrictions on disclosure to protect our intellectual property rights. Our
success depends in part on our ability to obtain new patents and licenses and to
preserve other intellectual property rights covering our products. We intend to
continue to seek patents on our inventions when appropriate. The process of
seeking patent protection can be time consuming and expensive and we cannot
assure you that any new patent applications will be approved, that any patents
that may issue will protect our intellectual property or that any issued patents
will not be challenged by third parties or will be sufficient in scope or
strength to provide meaningful protection or any commercial advantage to us.
Other parties may independently develop similar or competing technology or
design around any patents that may be issued to us. We cannot be certain that
the steps we have taken will prevent the misappropriation of our intellectual
property, particularly in foreign countries where the laws may not protect our
proprietary rights as fully as in the United States.

We may become subject to infringement claims.

         Although we do not believe that our products infringe the proprietary
rights of any third parties, we have in the past been subject to infringement
claims and third parties might assert infringement claims against us or our
customers in the future. Furthermore, we may initiate claims or litigation
against third parties for infringement of our proprietary rights or to establish
the validity of our proprietary rights. Litigation, either as plaintiff or
defendant, would cause us to incur substantial costs and divert management
resources from productive tasks. Any litigation, regardless of the outcome,
could harm our business.

                                      -4-


         If it appears necessary or desirable, we may seek licenses to
intellectual property that we are allegedly infringing. We may not be able to
obtain licenses on acceptable terms. The failure to obtain necessary licenses or
other rights could harm our business.

We have many competitors and we may not be able to compete effectively.

         We experience competition from a variety of sources with respect to
virtually all of our products, although we do not know of any single entity that
competes with us across the full range of our products, systems and services.
Competition in the markets that we serve is based on a number of factors,
including price, technology, applications experience, know-how, availability of
financing, reputation, product warranties, reliability, service and
distribution. Many of our current and potential competitors have greater name
recognition and substantially greater financial, marketing and other resources
than we do. These greater resources could, for example, allow our competitors to
develop technology, products and services superior to our own. As a result, we
may not be able to compete effectively with current or future competitors.

We may not be able to develop the new products or acquire the rights to new
products necessary to remain competitive.

         The water purification industry is characterized by ongoing
technological developments and changing customer requirements. As a result, our
success and continued growth depend, in part, on our ability to develop or
acquire rights to and successfully introduce into the marketplace enhancements
of existing products or new products that incorporate technological advances,
meet customer requirements and respond to products developed by our competition.
There can be no assurance that we will be successful in developing or acquiring
such rights to products on a timely basis or that such products will adequately
address the changing needs of the marketplace.

We may not be able to adapt to changes in technology and government regulation
fast enough to remain competitive.

         The water purification industry is characterized by changing
technology, competitively imposed process standards and regulatory requirements,
each of which influences the demand for our products and services. Changes in
legislative, regulatory or industrial requirements may render certain of our
purification products and processes obsolete. Acceptance of new products may
also be affected by the adoption of new government regulations requiring
stricter standards. Our ability to anticipate changes in technology and
regulatory standards and to develop and introduce new and enhanced products
successfully on a timely basis will be a significant factor in our ability to
grow and to remain competitive. There can be no assurance that we will be able
to achieve the technological advances that may be necessary for us to remain
competitive or that certain of our products will not become obsolete. In
addition, we are subject to the risks generally associated with new product
introductions and applications, including lack of market acceptance, delays in
development, or failure of products to operate properly.

A portion of our sales is dependent upon our customers' spending cycles for
capital equipment.

         The sale of capital equipment within the water purification industry is
cyclical and influenced by various economic factors including interest rates and
general fluctuations of the business cycle. Our Equipment Business Group and our
Ultrapure Water Group each derive a significant portion of its revenue from the
sale of capital equipment. While we sell capital equipment to customers in
diverse industries and in domestic and international markets, cyclicality of
capital equipment sales and general economic conditions could have an adverse
effect on our revenues and profitability.

                                      -5-


The acquisition of the Ecolochem Group may result in a loss of customers,
strategic partners and suppliers.

         The acquisition of the Ecolochem Group may have the effect of
disrupting customer relationships. Some of our customers or potential customers
and those of the Ecolochem Group may delay or alter buying patterns as they
evaluate the likelihood of successful integration of the Ecolochem Group's
business following the acquisition. Other customers may seek alternative sources
of products or services due to, among other reasons, a desire not to do business
with us or perceived concerns that we may not continue to support certain
products or services. In addition, by increasing the breadth of our business,
the acquisition may make it more difficult for us to enter into relationships
with customers and strategic partners, some of whom may view us as a more direct
competitor than we were prior to the acquisition. Therefore, we could experience
some customer attrition as a result of the acquisition.

         In addition, certain customers of the Ecolochem Group have the right to
terminate their agreements with the Ecolochem Group as a result of the
acquisition. Some or all of those customers may exercise that right, resulting
in the loss of related revenue and profits. The indemnification obligations of
the owners of the Ecolochem Group with respect to any such terminations may not
fully compensate us for the loss of those customers or the related revenue and
profit.

         Difficulties in integrating operations could also result in the loss of
strategic partners and suppliers and potential disputes or litigation with
customers, strategic partners, suppliers, resellers or others. There can be no
assurance that any steps by management to counter such potential increased
customer, strategic partner or supplier attrition will be effective.

         Failure by management to control customer, strategic partner and
supplier attrition could have a material adverse effect on our business,
financial condition and operating results.

The results of operations of the Ecolochem Group tend to fluctuate because of
the weather conditions that affect its customers.

         Demand for the mobile water treatment services offered by the Ecolochem
Group tends to increase during periods of severe hot or cold weather resulting
in increased revenues and earnings. The absence of severe weather may adversely
impact the revenue and operating results of the Ecolochem Group.

We must comply with significant environmental regulations, which can be
difficult and expensive.

         We are subject to a variety of federal, state and local governmental
regulations related to the use, storage, discharge and disposal of toxic,
volatile or otherwise hazardous chemicals used in our manufacturing processes.
Although we believe that our activities conform to presently applicable
environmental regulations, the failure to comply with present or future
regulations could result in fines being imposed on us, suspension of production
or a cessation of operations. Any failure by us to control the use of, or
adequately restrict the discharge of, hazardous substances, or otherwise comply
with environmental regulations, could subject us to significant future
liabilities. In addition, we cannot assure you that past use or disposal of
environmentally sensitive materials in conformity with then existing
environmental laws and regulations will not result in remediation or other
significant liabilities under current or future environmental laws or
regulations.

We depend on key personnel, the loss of whom could harm our business.

         We have been and are presently dependent upon the continued efforts of
our senior management team, including Douglas R. Brown, our President and Chief


                                      -6-


Executive Officer. The loss of the services of Mr. Brown or any other members of
our senior management team could have a material adverse effect on our ability
to achieve our objectives. We will enter into an employment agreement with Mr.
Lyman Dickerson, the President of Ecolochem, Inc., with the intent of providing
Mr. Dickerson with sufficient incentive to remain employed by us. However, it
cannot be assured that he will remain employed with us.

         The loss of our key personnel, including those of the Ecolochem Group,
could adversely affect our ability to manage our business. We believe that the
continued service of our executive officers and the executive officers of the
Ecolochem Group will be important to our future growth and competitiveness. Our
employees and those of the Ecolochem Group are entitled to voluntarily terminate
their relationship with us or with the Ecolochem Group, typically without any,
or with only minimal, advance notice. The process of finding additional trained
personnel to carry out our strategy could be lengthy, costly and disruptive. We
might not be able to retain the services of all of our or the Ecolochem Group's
key employees or a sufficient number of them to execute our plans. In addition,
we might not be able to continue to attract new employees as required.

         The loss of the services of any member of our or the Ecolochem Group's
management team, or of any other key employee, could divert management's time
and attention, increase our expenses and adversely affect our ability to conduct
our business efficiently.

If we are unable to continue to hire and retain skilled technical and scientific
personnel, then we will have trouble developing products.

         Our success depends largely upon the continued service of our
management and scientific staff and our ability to attract, retain and motivate
highly skilled scientific, management and marketing personnel. We face
significant competition for such personnel from other companies, research and
academic institutions, government and other organizations who may better be able
to attract such personnel. The loss of key personnel or our inability to hire
and retain personnel who have technical and scientific backgrounds could
materially adversely affect our product development efforts and our business.

If certain intangible assets acquired in the acquisition of the Ecolochem Group
subsequently become impaired, we may be required to write off, or reduce the
value of, those intangible assets, which would adversely impact our financial
results during the periods in which they occur.

         We currently expect to record approximately $183.8 million of goodwill
and $73 million of other intangible assets in connection with the acquisition of
the Ecolochem Group. Goodwill associated with the acquisition will be required
to be tested at least annually for impairment. Other intangible assets will be
amortized over their estimated useful lives. If the goodwill or other intangible
assets are deemed to be impaired in the future, we will be required to reduce
the value of those assets or to write them off completely, which would reduce
our reported financial results during the periods in which such determination is
made. If we are required to write down or write off all or a portion of those
assets, or if financial analysts or investors believe we may be required to take
such action in the future, the prices at which our common stock trades may be
adversely affected.

We may not derive any income tax benefits from the tax election which we
currently intend to make.

         We may elect to make, with the former shareholders of Ecolochem, Inc.
and Ecolochem International, Inc., an election under Section 338(h)(10) of the
Internal Revenue Code of 1986, as amended (the "Code"), with respect to the
acquisition of Ecolochem, Inc., Ecolochem International, Inc. or both. If a
valid election is made under Section 338(h)(10) of the Code, we will generally
be able to treat the acquisition of the stock of any company with respect to
which such election is made as if new subsidiaries of ours had acquired the
assets of such company in a taxable transaction for federal income tax purposes,
and, as a result, after the acquisition, the assets of such company will have a
tax basis generally equal to the cash and other property paid by us for such


                                      -7-


company plus any liabilities of such company that are assumed in the
transaction.

         The principal tax advantage of making an election under Section
338(h)(10) of the Code is that our new subsidiary or subsidiaries, as the case
may be, will be able to depreciate or amortize the new federal income tax basis
of depreciable or amortizable assets over time periods specified in the Code.
For intangible assets, that time period is generally 15 years.

         We may not be eligible to make an election under Section 338(h)(10) of
the Code with respect to Ecolochem, Inc., Ecolochem International, Inc. or both.
Currently, we intend to make an election under Section 338(h)(10) of the Code
only with respect to Ecolochem, Inc., but we may conclude to make an election
under Section 338(h)(10) of the Code with respect to Ecolochem International,
Inc. as well. Furthermore, even if a valid election under Section 338(h)(10) of
the Code is made, the depreciation and amortization deductions with respect to
certain assets acquired from the Ecolochem Group may not be available to us. As
a result, your decision to buy our common stock should not be based on any tax
benefits associated with such an election or on any other tax benefits
associated with the acquisition.

         If we make an election under Section 338(h)(10) of the Code, we will be
required to pay additional amounts to certain of the former owners of the
Ecolochem Group. These amounts will be significant.

Following the closing of the acquisition of the Ecolochem Group, we will be
subject to significant influence by the former owners of the Ecolochem Group.

         Following the closing of the acquisition, the former owners of the
Ecolochem Group will beneficially own approximately 20% of our common stock. As
a result, they have a strong influence on matters requiring approval by our
stockholders, such as the election of directors and most corporate actions,
including mergers and acquisitions. In addition, the former owners of the
Ecolochem Group will be entitled to designate two members of our Board of
Directors. These directors will have the opportunity to participate in all
matters brought before the Board of Directors. Moreover, Mr. Lyman Dickerson,
the President of Ecolochem, Inc., will have the opportunity to become the
Chairman of our Board of Directors pursuant to the terms of the Stockholders
Agreement to be entered into in connection with the acquisition of the Ecolochem
Group. Collectively, these arrangements will allow the former owners of the
Ecolochem Group to have significant participation in matters affecting us.

Future sales of our common stock by the former owners of the Ecolochem Group
could depress the market price of our common stock.

         While the former owners of the Ecolochem Group will be subject to
restrictions on their ability to resell a portion of the shares of common stock
issued to them in connection with our acquisition of the Ecolochem Group during
the six months following the closing of the acquisition, they will be entitled
to dispose of a significant number of shares in the public market, which could
cause the market price of our common stock to decrease significantly. All of the
former owners of the Ecolochem Group are required to enter into an agreement
under which they agree not to sell more than 10% of the shares of common stock
issuable to them in the acquisition for a period of six months following the
closing of the acquisition, subject to certain exceptions. Such restrictions
will lapse six months after the closing of the acquisition and the former owners
of the Ecolochem Group will then have no limitations on the number of shares
they can sell in the public market. If such persons sell a significant number of
shares of the common stock in the open market, our stock price could decline.

Substantial expenses will be incurred and payments made even if the acquisition
of the Ecolochem Group is not completed.

                                      -8-


         The acquisition may not be completed. Whether or not the acquisition is
completed, we will incur substantial expenses in pursuing the acquisition,
including:

o    Financial  advisory  fees  (certain  of  which  are  conditioned  upon  the
     consummation of the acquisition) and expenses;

o    Fees and expenses incurred in connection with the proposed financing of the
     acquisition; and

o    Costs and expenses for services  provided by our lawyers,  accountants  and
     other advisors.

         If the acquisition is completed, the transaction costs and expenses
attributable to advisory, legal and accounting services incurred by us will be
capitalized as a component of the purchase price.

         We expect to charge certain other transaction costs and expenses during
the periods in which they are incurred, which will reduce earnings or increase
losses during those periods. We might not be able to manage these
acquisition-related costs effectively, and they could be higher than are
currently estimated. If these costs are not managed effectively, our business
operations, financial results and stock price could be adversely affected.

         The costs and expenses we incur in connection with the acquisition,
other than certain fees payable to our financial advisor, must be paid even if
the acquisition is not completed. If the acquisition is not completed, these
expenses will reduce earnings or increase losses during the period in which it
is determined the acquisition will not be completed. In addition, under certain
circumstances if the acquisition is not completed, we may be required to pay a
termination fee of up to $13.2 million or in other instances to pay the
reasonable costs and expenses of the owners of the Ecolochem Group of up to a
maximum of $4.5 million.

Failure to complete the acquisition could cause our stock price to decline.

         If the acquisition is not completed for any reason, our stock price may
decline to the extent that the current market price reflects a market assumption
that the acquisition will be completed or the market's perceptions why the
acquisition was not consummated. In addition, our stock price may decline
because costs related to the acquisition, such as legal, accounting and certain
financial advisor fees, must be paid even if the acquisition is not completed,
adversely affecting our earnings during the period for which such costs are
recognized.

Failure of any of the members of the Ecolochem Group to be a "pass-through"
entity for United States federal and other tax purposes could increase our cost
of the cost of the acquisition.

         The owners of the Ecolochem Group have represented in the purchase
agreement that each of the members of the Ecolochem Group is a "pass-through"
entity for United States federal income tax purposes. Specifically, the owners
of the Ecolochem Group have represented that each of Ecolochem and Ecolochem
International, Inc. is a "Subchapter S Corporation" under the Code, and that
each of Moson Holdings, LLC and Ecolochem S.A.R.L. is treated as a "partnership"
under the Code for federal tax purposes. Accordingly, except in limited
circumstances, the Ecolochem Group does not, and has not for a substantial
period, paid income taxes at the entity level either to the United States or to
many state and local jurisdictions (with certain exceptions). If it were
ultimately determined that any member of the Ecolochem Group was not a valid
pass-through entity for tax purposes, that entity could be subject to tax,
penalties, additions to tax and interest for prior periods. The owners of the
Ecolochem Group are required to indemnify us for any taxes attributable to
periods prior to the acquisition, but there can be no assurance that any such
amount will actually be paid. Any significant tax, penalties, additions to tax
and interest for prior periods which we pay and for which we are not indemnified


                                      -9-


by the owners of the Ecolochem Group could have a material adverse effect on our
business, financial condition and operating results.

               SPECIAL NOTE REGARDING FORWARD-LOOKING INFORMATION

         Certain statements and assumptions contained, or incorporated by
reference, in this prospectus constitute forward-looking statements within the
meaning of Section 27A of the Securities Act of 1933, as amended, and Section
21E of the Securities Exchange Act of 1934, as amended. These statements include
those that predict, forecast, indicate or imply future results, performance or
achievements.

         Any statements contained in this prospectus, including statements to
the effect that Ionics or its management "believes," "expects," "anticipates,"
"plans," "may," "will," "projects," "continues," or "estimates" or statements
concerning "potential" or "opportunity" or other variations thereof or
comparable terminology or the negative thereof, that are not statements of
historical fact should be considered forward-looking statements.

         These forward-looking statements are based on current views and
assumptions and are neither promises nor guarantees but are subject to risks,
uncertainties and other factors that could cause actual results to differ
materially from current expectations as described in such forward-looking
statements. In connection with the forward-looking statements appearing in this
prospectus, you should carefully consider the matters discussed under the
caption "Risk Factors" beginning on page 1, and the other risk factors described
in Ionics' filings with the SEC, including its Proxy Statement dated January 9,
2004 and its Annual Report on Form 10-K for the year ended December 31, 2002, as
amended. We do not assume any obligation to update any forward-looking statement
we make, except as required by law.


                                      -10-



                                 USE OF PROCEEDS

         We will not receive any of the proceeds from the sale of our common
stock by the selling stockholders. The selling stockholders will receive all of
the net proceeds from any sale of the shares of common stock being sold by the
selling stockholders pursuant to this prospectus.

         The selling stockholders will pay any underwriting discounts and
commissions, all transfer taxes, and all expenses incurred by the selling
stockholders for brokerage, accounting, tax or legal services (except that we
have agreed to pay the fees and disbursements of one law firm representing the
selling stockholders on behalf of the selling stockholders) or any other
expenses incurred by the selling stockholders in disposing of the shares. We
will bear all other costs, fees and expenses incurred in effecting the
registration of the shares covered by this prospectus, including, without
limitation, all registration and filing fees, New York Stock Exchange listing
fees and fees and expenses of our counsel, and fees and expenses of one counsel
to the selling stockholders and our accountants.

                              SELLING STOCKHOLDERS

         The following table sets forth, to our knowledge, the name and number
of shares of our common stock beneficially owned by each of the selling
stockholders as of the consummation of our acquisition of Ecolochem, Inc. and
its affiliated companies. Beneficial ownership is determined in accordance with
the rules of the Securities and Exchange Commission, and includes voting or
investment power with respect to shares. Unless otherwise indicated below, to
our knowledge, all persons named in the table have sole voting and investment
power with respect to their shares of common stock and except as set forth in
the footnotes to the table. The inclusion of any shares in this table does not
constitute an admission of beneficial ownership for the person or trust named
below. The table has been prepared on the basis of information furnished to us
by or on behalf of the selling stockholders. As of January 14, 2004, there were
approximately 17,903,386 shares of our common stock outstanding.





                                               Shares of Common Stock                         Shares of Common Stock to
                                                    Beneficially                                   be Beneficially
                                                   Owned Prior to                              Owned After Offering(1)
                                                     Offering(1)

                                                                          Number of Shares
                                                                          of Common Stock
                                                                           Being Offered
          Name of Selling Stockholder                                    Pursuant to this
                                                                           Prospectus(2)

                                                 Number      Percent                            Number        Percent

                                                                                                           
Lyman B. Dickerson(3)                                                                              0             *
Douglas G. Dickerson(4)                                                                            0             *
The Estate of Richard C. Dickerson(5)                                                              0             *
The Richard Dickerson Revocable Trust Dated                                                        0             *
   March 5, 1993, or any Successor Trustee,
   as amended (6)
The Lyman Dickerson Irrevocable Trust, dated                                                       0             *
   July 1, 2001 (7)
The Douglas Dickerson Irrevocable Trust No.                                                        0             *
   3, dated July 1, 1991 (8)
The Richard Dickerson Irrevocable Trust No.                                                        0             *
   3, dated July 1, 1991 (9)
---------------------


                                      -11-


* Less than one percent.

(1)  In connection with the consummation of our acquisition of the Ecolochem
     Group the selling stockholders will agree not to transfer, during the six
     months following the consummation of the acquisition, more than 10% of the
     shares of our common stock issued to them by us in connection with the
     acquisition other than transfers to certain related persons. The selling
     stockholders will also agree to certain restrictions on the sale or other
     transfer of such shares of our common stock to certain competitors of ours.
     Notwithstanding the foregoing, we do not know when or in what amounts a
     selling stockholder may offer shares for sale. The selling stockholders may
     sell any or all of the shares offered by this prospectus. Because the
     selling stockholders may offer all or some of the shares pursuant to this
     offering, and because there are currently no agreements, arrangements or
     understandings with respect to the sale of any of the shares, we cannot
     estimate the number of the shares that will be held by the selling
     stockholders after completion of the offering. However, for purposes of
     this table, we have assumed that, after completion of the offering, none of
     the shares covered by this prospectus will be held by the selling
     stockholders.
(2)  Pursuant to Rule 416 under the Securities Act of 1933, as amended, this
     prospectus will also cover an indeterminable number of additional shares of
     common stock that may be issued to prevent dilution resulting from stock
     splits, stock dividends or similar transactions affecting the shares to be
     offered by the selling stockholders.
(3)  Includes ______ shares held by The Lyman B. Dickerson Revocable Trust Dated
     September 9, 1996 or any Successor Trustee, as amended, of which Lyman B.
     Dickerson is the sole trustee.
(4)  Includes ______ shares held by The Douglas G. Dickerson Revocable Trust
     Dated June 22, 1988 or any Successor Trustee, as amended, of which Douglas
     G. Dickerson is the sole trustee.
(5)  Douglas G. Dickerson and Marguerite W. Dickerson, as co-executors, share
     voting and dispositive power with respect to these shares.
(6)  Douglas G. Dickerson and Marguerite W. Dickerson, as co-trustees, share
     voting and dispositive power with respect to these shares.
(7)  Lyman B. Dickerson, as trustee and Charles C. Kline, as independent trustee
     share voting and dispositive power with respect to these shares.
(8)  Douglas G. Dickerson, as trustee and Frederick T. Stant, III, as
     independent trustee share voting and dispositive power with respect to
     these shares.
(9)  Douglas G. Dickerson and Marguerite W. Dickerson as co-trustees and
     Frederick T. Stant, as independent trustee, share voting and dispositive
     power with respect to these shares.

         Each of the selling stockholders is to receive the shares of our common
stock held by them in connection with the consummation of our acquisition of
Ecolochem, Inc. and its affiliated companies. We intend to appoint Mr. Lyman
Dickerson to our Board of Directors simultaneously with the closing of the
acquisition. Mr. Lyman Dickerson has substantial direct and indirect interests
in the acquisition. All of the selling stockholders may be considered associates
of Mr. Lyman Dickerson under the rules of the Securities Exchange Act of 1934,
as amended. In addition, upon the closing of the acquisition, we will enter into
an employment agreement with Mr. Lyman Dickerson. The terms of this agreement
provide that Mr. Lyman Dickerson will be employed as the Vice President of our
Water Systems Division (which includes, among other operations, the Ecolochem
Group and its respective subsidiaries and our Ultrapure Water and Industrial
Water operations). In this position, Mr. Lyman Dickerson will be the senior
executive officer for the Division and will be responsible for managing the
integration of the Ecolochem Group with our existing operations. The term of
this agreement is for two years unless sooner terminated for "cause" (as defined
therein) or under certain other circumstances. Under the terms of his employment
agreement, Mr. Lyman Dickerson will be entitled to, among other things: an
initial base annual salary of $250,000; participation in our executive bonus
program and stock option plans (as determined by our Board of Directors);
participation in our benefit plans; and a severance benefit should his
employment agreement be terminated by us prior to the expiration of its term for
reasons other than "cause".

         Each selling stockholder represented to us that he or it acquired the
shares of common stock for investment and not with a view to any public
distribution thereof in violation of any of the registration requirements of the
Securities Act of 1933, as amended. In addition, each selling stockholder has
represented that he or it qualifies as an "accredited investor" as such term is
defined in Rule 501 of Regulation D under the Securities Act of 1933, as
amended. In recognition of the fact that the selling stockholders may desire the
ability to sell the shares when they consider it appropriate, in connection with


                                      -12-


the acquisition we agreed to file with the Securities and Exchange Commission a
registration statement (of which this prospectus is a part) to permit the resale
of the shares from time to time and to use our commercially reasonable efforts
to keep the registration statement effective for the period from effectiveness
of the registration statement of which this prospectus forms a part until the
first date on which (i) the selling stockholders cease to hold in the aggregate
a number of shares of common stock equal to the lesser of (a) at least 5% of the
number of outstanding shares of our common stock as of the close of business on
the day immediately preceding the date upon which we consummate the acquisition
of Ecolochem, Inc. and its affiliated companies and (b) at least 5% of the
number of outstanding shares of our Common Stock as of the date of measurement;
(ii) following the first anniversary of the date hereof, the number of
outstanding shares of our common stock which were first issued to the selling
stockholders in connection with the consummation of the acquisition of
Ecolochem, Inc. and its affiliated companies (and any securities issued or
distributed in respect of such shares by way of conversion, dividend, stock
split or other distribution, merger, consolidation, exchange, recapitalization
or reclassification) and are still held by the selling stockholders and their
permitted assigns equal less than 1% of our then outstanding shares of our
common stock, or (iii) no selling stockholder or their permitted assigns are an
"affiliate" of ours as such term is defined in Rule 144 of the Securities Act of
1933, as amended and all shares of our common stock first issued to the selling
stockholders in connection with the consummation of the acquisition of
Ecolochem, Inc. and its affiliated companies (and any securities issued or
distributed in respect of such shares by way of conversion, dividend, stock
split or other distribution, merger, consolidation, exchange recapitalization or
reclassification) may be sold in a single transaction under Rule 144(k) of the
Securities Act of 1933, as amended.

         Based on representations by the selling stockholders, to the best of
our knowledge, none of the selling stockholders had a material relationship with
us or any of our affiliates within the three-year period ending on the date of
this prospectus.


                              PLAN OF DISTRIBUTION

         The shares of our common stock covered by this prospectus may be
offered and sold from time to time by the selling stockholders. The term
"selling stockholders" includes pledgees, donees, transferees, designees, or
other successors-in-interest selling shares received after the date of this
prospectus from a selling stockholder as a gift, pledge, distribution of trust
proceeds or other non-sale related transfer provided that any such pledgee,
donee, transferee, designee or other successor-in-interest is either (i) another
selling stockholder, (ii) the spouse, child, grandchild, aunt, uncle, niece or
nephew of any selling stockholder, (iii) an heir, executor, administrator,
testamentary trustee, legatee or beneficiary of any selling stockholder or (iv)
a trust, the beneficiaries of which, or a corporation or partnership, the
stockholders or general and limited partners of which, include only one or more
of the persons specified in clauses (i), (ii) and (iii). The selling
stockholders will act independently of us in making decisions with respect to
the timing, manner and size of each sale. Such sales may be made on one more
exchanges or in the over-the-counter market or otherwise, at prices and under
terms then prevailing or at prices related to the then-current market price or
in negotiated transactions. The selling stockholders may sell their shares by
one or more of, or a combination of, the following methods:

o    purchases by a broker-dealer as principal and resale by such  broker-dealer
     for it own account pursuant to this prospectus;

o    ordinary  brokerage  transactions  and  transactions  in which  the  broker
     solicits purchasers

o    block trades in which the broker-dealer so engaged will attempt to sell the
     shares  as agent but may  position  and  resell a  portion  of the block as
     principal to facilitate the transaction;

o    in privately negotiated transactions;

o    in options transactions; and

o    through other means.

                                      -13-


         In addition, any shares that qualify for sale pursuant to Rule 144 of
the Securities Act of 1933, as amended, may be sold under Rule 144 rather than
pursuant to this prospectus. No selling stockholder has entered into any
agreement with a prospective underwriter and there is no assurance that any such
agreement will be entered into.

         To the extent required, this prospectus may be amended or supplemented
from time to time to describe a specific plan of distribution. In connection
with distributions of the shares or otherwise, the selling stockholders may
enter into hedging transactions with broker-dealers or other financial
institutions. In connection with such transactions, broker-dealers or other
financial institutions may engage in short sales of the common stock in the
course of hedging the positions they assume with selling stockholders. The
selling stockholders may also sell the common stock short and redeliver the
shares to close out such short positions. The selling stockholders may also
enter into option or other transactions with broker-dealers or other financial
institutions which require the delivery to such broker-dealer or other financial
institution of shares offered by this prospectus, which shares such
broker-dealer or other financial institution may resell pursuant to this
prospectus (as supplemented or amended to reflect such transaction). The selling
stockholders may also pledge shares to a broker-dealer or other financial
institution, and, upon a default, such broker-dealer or other financial
institution, may effect sales of the pledged shares pursuant to this prospectus
(as supplemented or amended to reflect such transaction).

         In effecting sales, broker-dealers or agents engaged by the selling
stockholders may arrange for other broker-dealers to participate. Broker-dealers
or agents may receive commissions, discounts or concessions from the selling
stockholders in amounts to be negotiated immediately prior to the sale.

         In offering the shares covered by this prospectus, the selling
stockholders and any broker-dealers who execute sales for the selling
stockholders may be deemed to be "underwriters" within the meaning of the
Securities Act of 1933, as amended, in connection with such sales. Any profits
realized by the selling stockholders and compensation of any broker-dealer may
be deemed to be underwriting discounts and commissions.

         In order to comply with the securities laws of certain jurisdictions,
the shares offered by this prospectus may need to be offered or sold in such
jurisdictions only through registered or licensed brokers or dealers.

         Under applicable rules and regulations under the Securities Exchange
Act of 1934, any person engaged in a distribution of the shares of common stock
covered by this prospectus may be limited in their ability to engage in market
activities with respect to such shares. The selling stockholders, for example,
will be subject to applicable provisions of the Securities Exchange Act of 1934
and the rules and regulations under it, including, without limitation Regulation
M, which provisions may restrict certain activities of the selling stockholders
and limit the timing of purchases and sales of any shares of common stock by the
selling stockholders. Furthermore, under Regulation M, persons engaged in a
distribution of securities are prohibited from simultaneously engaging in market
making and certain other activities with respect to such securities for a
specified period of time prior to the commencement of such distributions,
subject to specified exceptions or exemptions. The foregoing may affect the
marketability of the shares offered by this prospectus.

         We have agreed to pay the fees and expenses incurred in effecting the
registration of the shares covered by this prospectus, including, without
limitation, all registration and filing fees, New York Stock Exchange listing
fees, and fees and expenses of our counsel, one counsel to the selling
stockholders and our accountants. The selling stockholders will pay any
underwriting discounts and commissions and expenses incurred by the selling
stockholders in disposing of the shares. We will not receive any of the proceeds
from the sale of our common stock by the selling stockholders.

                                      -14-


         We have agreed to indemnify the selling stockholders against certain
liabilities, including certain liabilities under the Securities Act of 1933, as
amended.

         We have agreed to use our commercially reasonable efforts to keep the
registration statement effective for the period from effectiveness of the
registration statement of which this prospectus forms a part until the first
date on which (i) the selling stockholders cease to hold in the aggregate a
number of shares of common stock equal to the lesser of (a) at least 5% of the
number of outstanding shares of our common stock as of the close of business on
the day immediately preceding the date upon which we consummate the acquisition
of Ecolochem, Inc. and its affiliated companies and (b) at least 5% of the
number of outstanding shares of our common stock at the date of measurement;
(ii) following the first anniversary of the date hereof, the number of
outstanding shares of our common stock which were first issued to the selling
stockholders in connection with the consummation of the acquisition of
Ecolochem, Inc. and its affiliated companies (and any securities issued or
distributed in respect of such shares by way of conversion, dividend, stock
split or other distribution, merger, consolidation, exchange, recapitalization
or reclassification) and are still held by the selling stockholders and their
permitted assigns equal less than 1% of our then outstanding shares of our
common stock, or (iii) no selling stockholder or their permitted assigns is an
"affiliate" of ours as such term is defined in Rule 144 of the Securities Act of
1933, as amended, and all shares of our common stock first issued to the selling
stockholders in connection with the consummation of the acquisition of
Ecolochem, Inc. and its affiliated companies (and any securities issued or
distributed in respect of such shares by way of conversion, dividend, stock
split or other distribution, merger, consolidation, exchange recapitalization or
reclassification) may be sold in a single transaction under Rule 144(k) of the
Securities Act of 1933, as amended. We may suspend the selling stockholders'
rights to resell shares under this prospectus under certain limited
circumstances.

     Equiserve Trust Company,  N.A., 150 Royall Street, Canton, MA 02021, is the
transfer agent for the shares of our common stock.

                                  LEGAL MATTERS

         The validity of the shares of our common stock offered hereby will be
passed upon for us by Stephen Korn, Vice President and General Counsel of
Ionics. Mr. Korn beneficially owns 128,816 shares of our common stock, which
number includes 126,000 shares subject to options, as to which Mr. Korn has the
right to acquire beneficial ownership, and 1,593 shares (as of January 14, 2004)
in our Section 401(k) Plan for the account of Mr. Korn.

                                     EXPERTS

     The consolidated  financial statements as of December 31, 2002 and 2001 and
for each of the three years in the period ended  December 31, 2002  incorporated
in this Prospectus by reference to Ionics, Incorporated's Current Report on Form
8-K dated  December  24,  2003,  have been so  incorporated  in  reliance on the
reports of  PricewaterhouseCoopers  LLP, independent  accountants,  given on the
authority of said firm as experts in auditing and accounting.


     The combined  financial  statements of the Ecolochem Group  incorporated in
this  prospectus by reference to our Proxy Statement dated January 9, 2004, have
been so  incorporated  in  reliance  upon the  report of KPMG  LLP,  independent
accountants  given on the  authority  of said firm as  experts in  auditing  and
accounting.

                                      -15-


                       WHERE YOU CAN FIND MORE INFORMATION

     We file annual,  quarterly and current reports,  proxy statements and other
information with the Securities and Exchange  Commission.  You may read and copy
any  document  we file  with  the  Securities  and  Exchange  Commission  at the
Securities and Exchange  Commission's public reference room at 450 Fifth Street,
N.W.,  Washington,  D.C.  20549.  You should call the  Securities  and  Exchange
Commission at 1-800-SEC-0330 for further  information on operation of the public
reference  room.  Our  Securities  and  Exchange  Commission  filings  are  also
available to the public from the Securities and Exchange  Commission's  Internet
site at http://www.sec.gov and from our Internet site at  http://www.ionics.com.
In addition,  these  materials  may be read at the offices of the New York Stock
Exchange, 20 Broad Street, New York, New York 10005.

     This prospectus is part of a registration  statement that we filed with the
Securities and Exchange  Commission.  The registration  statement  contains more
information  than this prospectus  regarding us and our common stock,  including
certain  exhibits  and  schedules.  You can  obtain  a copy of the  registration
statement  from the  Securities  and Exchange  Commission at the address  listed
above or from the Securities and Exchange Commission's Internet site.

                 INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

     The  Securities  and  Exchange  Commission  allows  us to  "incorporate  by
reference" the  information we file with them,  which means that we can disclose
important  information  to  you  by  referring  you  to  those  documents.   The
information  incorporated  by  reference  is  considered  to  be  part  of  this
prospectus. We incorporate by reference the following documents:

     (a) Our Annual  Report on Form 10-K for the fiscal year ended  December 31,
2002,  as amended by Form 10-K/A filed with the SEC on April 1, 2003,  Form 11-K
filed  with the SEC on June  26,  2003 and  Form  10-K/A  filed  with the SEC on
October 2, 2003;

     (b) Our Proxy  Statement  filed with the SEC on January 9, 2004 pursuant to
the  Securities  Exchange Act of 1934,  as amended,  which  contains the audited
combined  financial  statements for the Ecolochem Group as of September 30, 2003
and 2002, and for each of the years in the three-year period ended September 30,
2003  and the  unaudited  pro  forma  combined  condensed  balance  sheet  as of
September 30, 2003 and the unaudited pro forma combined condensed  statements of
operations  for the nine  months  ended  September  30, 2003 and the fiscal year
ended December 31, 2002, and the additional proxy  solicitation  materials filed
with the SEC on January 15,  2004  pursuant to the  Securities  Exchange  Act of
1934, as amended;

     (c) Our Quarterly  Reports on Form 10-Q for the fiscal quarters ended March
31, 2003 (as amended by Form 10-Q/A filed with the SEC on October 2, 2003), June
30, 2003 and September 30, 2003;

     (d) Our Current  Reports on Form 8-K filed on May 6, 2003,  August 1, 2003,
October 7, 2003,  November 4, 2003,  November  19,  2003,  November 26, 2003 and
December  24,  2003  (which  contains  our audited  financial  statements  as of
December  31, 2002 and 2001 and for each of the years in the  three-year  period
ended December 31, 2002); and

     (e) The section  entitled  "Description  of  Registrant's  Securities to be
Registered" contained in our Registration  Statement on Form 8-A, filed with the
SEC on September 27, 1990 pursuant to Section 12(g) of the  Securities  Exchange
Act of 1934, as amended.

     All documents we file with the  Securities  and Exchange  Commission  under
Sections 13(a),  13(c),  14 or 15(d) of the Securities  Exchange Act of 1934, as
amended,  subsequent to the date of this  prospectus and prior to the earlier of
the sale of all the shares of common stock  covered by this  prospectus  and the
termination  of the  offering  of the  shares of common  stock  covered  by this


                                      -16-


prospectus shall be deemed incorporated by reference into this prospectus and to
be a part hereof from the date of filing of such documents.

     Any  statement  contained  in a  document  incorporated  or  deemed  to  be
incorporated  by reference  herein shall be deemed to be modified or  superseded
for purpose of this prospectus to the extent that a statement  contained  herein
or in any other  subsequently  filed  document  which also is or is deemed to be
incorporated by reference herein modifies or supersedes such statement. Any such
statement so modified or superseded  shall not be deemed,  except as so modified
or superseded, to constitute a part of this prospectus.

     We will provide to each person,  including any beneficial  owner, to whom a
prospectus is delivered,  a copy of any or all of the information  that has been
incorporated  by reference in this  prospectus  (including  any exhibits to such
documents that are specifically  incorporated by reference in that  information,
but excluding  other  exhibits to such  documents)  but not delivered  with this
prospectus.  You may request a copy of these documents at no cost, by writing or
telephoning  Stephen  Korn,  Clerk,  Ionics,  Incorporated,   65  Grove  Street,
Watertown, MA 02472-2882, telephone (617) 673-4450.

         This prospectus is part of a registration statement we filed with the
Securities and Exchange Commission. You should rely only on the information
incorporated by reference, provided in this prospectus, or any supplement that
we have referred you to. We have authorized no one to provide you with different
information. You should not assume that the information in this prospectus or
any supplement is accurate as of any date other than the date on the front of
those documents. However, you should realize that the affairs of Ionics may have
changed since the date of this prospectus. This prospectus will not reflect such
changes. You should not consider this prospectus to be an offer or solicitation
relating to the securities in any jurisdiction in which such an offer or
solicitation relating to the securities is not authorized. Furthermore, you
should not consider this prospectus to be an offer or solicitation relating to
the securities if the person making the offer or solicitation is not qualified
to do so, or if it is unlawful for you to receive such an offer or solicitation.


                                      -17-



                                     PART II

                     INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14.  Other Expenses of Issuance and Distribution.

         The following table sets forth an estimate (other than with respect to
the Securities and Exchange Commission registration fee) of the expenses
expected to be incurred in connection with the issuance and distribution of the
securities being registered, all of which will be borne by Ionics, Incorporated
(except any underwriting discounts and commissions incurred by the selling
stockholders in disposing the shares):

Registration Fee -- Securities and Exchange Commission.....$    11,953.62
Accounting Fees and Expenses...............................$     5,000.00
Legal Fees and Expenses....................................$    20,000.00
Miscellaneous .............................................$     5,000.00
                                                           --------------
         TOTAL.............................................$    41,953.62
                                                           ==============


Item 15.  Indemnification of Directors and Officers.

         Ionics is permitted by the Massachusetts Business Corporation Law and
required by its By-laws to indemnify any director or officer or former director
or officer against all expenses and liabilities reasonably incurred by him or
her in connection with any legal action in which such person is involved by
reason of his position with Ionics unless he or she shall have been finally
adjudicated in any action, suit or proceeding not to have acted in good faith in
the reasonable belief that his action was in the best interests of Ionics. Such
indemnification shall include payment by Ionics of expenses incurred in
defending a civil or criminal action or proceeding in advance of the final
disposition of such action or defending a civil or criminal action or
proceeding, upon Ionics' receipt of the undertaking of the person indemnified to
repay such payment if such person shall be adjudicated not entitled to such
indemnification.

         Directors and officers of Ionics are also insured up to an aggregate of
$15,000,000 under a Directors' and Officers' Liability and Company Reimbursement
Policy, and up to an additional $5,000,000 under a Directors' and Officers'
Liability Policy.

         The Restated Articles of Organization of Ionics includes a provision
limiting the personal liability of directors of Ionics to its stockholders for
monetary damages for breaches of their fiduciary duty to the extent permitted by
the Massachusetts Business Corporation Law...

Item 16. Exhibits.

         The following exhibits, required by Item 601 of Regulation S-K, are
filed as a part of this Registration Statement. Exhibit numbers, where
applicable, in the left column correspond to those of Item 601 of Regulation
S-K.

Exhibit No.              Item and Reference
-----------              ------------------
2.1                      Purchase Agreement dated as of November 18, 2003
                         between the individuals and entities listed on Exhibit
                         A thereto and Ionics Incorporated (filed as Exhibit 2.1
                         to the Current Report on Form 8-K of Ionics dated
                         November 26, 2003 and incorporated herein by
                         reference).

                                      -II-1-


4.1                      Form of Stockholders Agreement among Ionics,
                         Incorporated and the Individuals and Entities listed on
                         Exhibit A thereto (filed as Annex B to the Proxy
                         Statement on Schedule 14A of Ionics filed on January 9,
                         2004 and incorporated herein by reference).

4.2                      Renewed Rights Agreement, dated as of August 19, 1997
                         between Registrant and BankBoston N.A. as Rights Agent
                         (filed as Exhibit 1 to the Current Report on Form 8-K
                         of Ionics dated August 27, 1997 and incorporated herein
                         by reference).

4.3                      Amendment  No. 1 dated as of November 17, 2003,  to the
                         Renewed Rights  Agreement dated August 19, 1997 between
                         Ionics,  Incorporated  and  EquiServe  Trust Company as
                         Rights Agent (and  successor in interest to  BankBoston
                         N.A.)(filed  as Exhibit  4.1 to the  Current  Report on
                         Form  8-K  of  Ionics  dated   November  26,  2003  and
                         incorporated herein by reference).

4.4                      Form of Common Stock Certificate (filed as Exhibit 4.2
                         to Annual Report on Form 10-K of Ionics for year ended
                         December 31, 1997 and incorporated herein by
                         reference).

5                        Opinion of Stephen Korn, Esquire (filed herewith).

23.1                     Consent of PricewaterhouseCoopers LLP (filed herewith).

23.2                     Consent of KPMG LLP (filed herewith)
23.3                     Consent of Stephen Korn, Esquire (included in
                         Exhibit 5).

24                       Power of Attorney (included on signature pages).

Item 17. Undertakings.

The undersigned registrant hereby undertakes:

         (1) To file, during any period in which offers or sales are being made,
a post-effective amendment to this registration statement:

                    (i)  To include any prospectus  required by Section 10(a)(3)
                         of the Securities Act of 1933, as amended;

                  (ii) To reflect in the prospectus any facts or events arising
after the effective date of the registration statement (or the most recent
post-effective amendment thereof) which, individually or in the aggregate,
represents a fundamental change in the information set forth in the registration
statement. Notwithstanding the foregoing, any increase or decrease in volume of
securities offered (if the total dollar value of securities offered would not
exceed that which was registered) and any deviation from the low or high and of
the estimated maximum offering range may be reflected in the form of prospectus
filed with the Securities and Exchange Commission pursuant to Rule 424(b) if, in
the aggregate, the changes in volume and price represent no more than 20 percent
change in the maximum aggregate offering price set forth in the "Calculation of
Registration Fee" table in the effective registration statement; and

                                      -II-2-


                  (iii) To include any material information with respect to the
plan of distribution not previously disclosed in the registration statement or
any material change to such information in the registration statement;

provided, however, that paragraphs (1)(i) and 1(ii) do not apply if the
information required to be included in a post-effective amendment by those
paragraphs is contained in periodic reports filed with or furnished to the
Commission by the registrant pursuant to Section 13 or Section 15(d) of the
Securities Exchange Act of 1934, as amended, that are incorporated by reference
in the registration statement.

         (2) That, for the purpose of determining any liability under the
Securities Act of 1933, as amended, each such post-effective amendment shall be
deemed to be a new registration statement relating to the securities offered
therein, and the offering of such securities at that time shall be deemed to be
the initial bona fide offering thereof.

         (3) To remove from registration by means of a post-effective amendment
any of the securities being registered which remain unsold at the termination of
the offering.

         The undersigned registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act of 1933, as amended, each
filing of the registrant's annual report pursuant to Section 13(a) or 15(d) of
the Securities Exchange Act of 1934, as amended (and, where applicable, each
filing of an employee benefit plan's annual report pursuant to Section 15(d) of
the Securities Exchange Act of 1934, as amended) that is incorporated by
reference in the registration statement shall be deemed to be a new registration
statement relating to the securities offered therein, and the offering of such
securities at that time shall be deemed to be the initial bona fide offering
thereof.

         Insofar as indemnification for liabilities arising under the Securities
Act of 1933, as amended, may be permitted to directors, officers and controlling
persons of the registrant pursuant to provisions described in Item 15 above, or
otherwise, the registrant has been advised that in the opinion of the Securities
and Exchange Commission such indemnification is against public policy as
expressed in the Securities Act of 1933, as amended, and is, therefore,
unenforceable. In the event that a claim for indemnification against such
liabilities (other than the payment by the registrant of expenses incurred or
paid by a director, officer or controlling person of the registrant in the
successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act of 1933, as amended, and will be
governed by the final adjudication of such issue.



                                      -II-3-



                                   SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the
registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-3 and have duly caused this
registration statement to be signed on its behalf by the undersigned, thereunto
duly authorized in the City of Watertown, Commonwealth of Massachusetts on
January 19, 2004.


                                    Ionics, Incorporated



                                    By:/s/ Douglas R. Brown
                                    -----------------------
                                    Douglas R. Brown
                                    President and Chief Executive Officer











                                Power of Attorney

Each person whose signature appears below on this registration statement hereby
constitutes and appoints Douglas R. Brown and Stephen Korn and each of them,
with full power to act without the other, his true and lawful attorney-in-fact
and agent, with full power of substitution and resubstitution, for him and in
his name, place and stead, in any and all capacities (until revoked in writing)
to sign any and all amendments (including post-effective amendments and
amendments thereto) to this registration statement of Ionics, Incorporated, and
to file the same, with all exhibits thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, granting unto said
attorneys-in-fact and agents, and each of them, full power and authority to do
and perform each and every act and thing requisite and necessary fully to all
intents and purposes as he or she might or could do in person thereby ratifying
and confirming all that said attorneys-in-fact and agents or any of them, or
their or his substitute or substitutes, may lawfully do or cause to be done by
virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, this registration
statement has been signed below by the following persons on behalf of the
Registrant and in the capacities and on the dates indicated.



Name                                     Capacity                                                  Date


                                                                                            
/s/ Douglas R. Brown                     President and Chief Executive Officer                    January 19, 2004
----------------------------------------
Douglas R. Brown                         (principal executive officer) and Director

/s/ Daniel M. Kuzmak                     Vice President, Finance and Chief Financial              January 19, 2004
----------------------------------------
Daniel M. Kuzmak                         Officer (principal financial officer)

 /s/ Anthony Di Paola                    Vice President and Corporate Controller                  January 19, 2004
----------------------------------------
Anthony Di Paola                         (principal accounting officer)

 /s/ Stephen L. Brown                    Director                                                 January 19, 2004
----------------------------------------
Stephen L. Brown

 /s/ Arthur L. Goldstein                 Chairman of the Board and Director                       January 19, 2004
----------------------------------------
Arthur L. Goldstein

                                         Director
----------------------------------------
Kathleen F. Feldstein

 /s/ William K. Reilly                   Director                                                 January 19, 2004
----------------------------------------
William K. Reilly

 /s/ John J. Shields                     Director                                                 January 19, 2004
----------------------------------------
John J. Shields

 /s/ Daniel I. C. Wang                   Director                                                 January 19, 2004
----------------------------------------
Daniel I. C. Wang

 /s/ Mark S. Wrighton                    Director                                                 January 19, 2004
----------------------------------------
Mark S. Wrighton

 /s/ Allen S. Wyett                      Director                                                 January 19, 2004
----------------------------------------
Allen S. Wyett





                                INDEX TO EXHIBITS

Exhibit No.              Item and Reference
-----------              ------------------
2.1                      Purchase Agreement dated as of November 18, 2003
                         between the individuals and entities listed on Exhibit
                         A thereto and Ionics Incorporated (filed as Exhibit 2.1
                         to the Current Report on Form 8-K of Ionics dated
                         November 26, 2003 and incorporated herein by
                         reference).

4.1                      Form of Stockholders Agreement among Ionics,
                         Incorporated and the Individuals and Entities listed on
                         Exhibit A thereto (filed as Annex B to the Proxy
                         Statement on Schedule 14A of Ionics filed on January 9,
                         2004 and incorporated herein by reference).

4.2                      Renewed Rights Agreement, dated as of August 19, 1997
                         between Registrant and BankBoston N.A. as Rights Agent
                         (filed as Exhibit 1 to the Current Report on Form 8-K
                         of Ionics dated August 27, 1997 and incorporated herein
                         by reference).

4.3                      Amendment  No. 1 dated as of November 17, 2003,  to the
                         Renewed Rights  Agreement dated August 19, 1997 between
                         Ionics,  Incorporated  and  EquiServe  Trust Company as
                         Rights Agent (and  successor in interest to  BankBoston
                         N.A.)(filed  as Exhibit  4.1 to the  Current  Report on
                         Form  8-K  of  Ionics  dated   November  26,  2003  and
                         incorporated herein by reference).

4.4                      Form of Common Stock Certificate (filed as Exhibit 4.2
                         to Annual Report on Form 10-K of Ionics for year ended
                         December 31, 1997 and incorporated herein by
                         reference).

5                        Opinion of Stephen Korn, Esquire (filed herewith).

23.1                     Consent of PricewaterhouseCoopers LLP (filed herewith).

23.2                     Consent of KPMG LLP (filed herewith)
23.3                     Consent of Stephen Korn, Esquire (included in
                         Exhibit 5).

24                       Power of Attorney (included on signature pages).






                                                                      EXHIBIT 5




                                                   January 19, 2004


Ionics, Incorporated
65 Grove Street
Watertown, Massachusetts 02472-2882

         Re:      S-3 Registration Statement

Ladies and Gentlemen:

         As General Counsel to Ionics, Incorporated, a Massachusetts corporation
(the "Company"), I have represented the Company in connection with the
preparation and filing of the Company's Form S-3 Registration Statement (the
"Registration Statement"), covering the sale to the public of up to 4,905,660
shares of the Company's common stock (the "Common Stock"), $1.00 par value per
share (the "Shares"), which may be sold by certain selling stockholders of the
Company as set forth in the Registration Statement.

         I have reviewed the corporate proceedings taken by the Board of
Directors of the Company with respect to the authorization and issuance of the
Shares. I have also examined and relied upon originals or copies, certified or
otherwise authenticated to my satisfaction, of all corporate records, documents,
agreements or other instruments of the Company and have made all investigations
of law and have discussed with the Company's officers all questions of fact that
I have deemed necessary or appropriate.

         Based upon and subject to the foregoing, I am of the opinion that the
Shares, when issued to the selling stockholders as described in the Registration
Statement, will be legally issued, fully paid and non-assessable.

         I hereby consent to the filing of this opinion as Exhibit 5 to the
Registration Statement and to the reference to my name in the prospectus
contained in the Registration Statement under the caption "Legal Matters."

                                                     Very truly yours,

                                                     /s/ Stephen Korn
                                                     ----------------
                                                     Stephen Korn
                                                     General Counsel






                                                                   Exhibit 23.1

                       CONSENT OF INDEPENDENT ACCOUNTANTS

         We hereby consent to the incorporation by reference in this
Registration Statement on Form S-3 of Ionics, Incorporated of our report dated
March 26, 2003, except for Note 6 and the second paragraph of Note 1, as to
which the date is December 23, 2003, relating to the financial statements of
Ionics, Incorporated, which appears in the Current Report on Form 8-K dated
December 24, 2003. We also consent to the reference to us under the heading
"Experts" in such Registration Statement.


/s/ PricewaterhouseCoopers LLP
------------------------------
PricewaterhouseCoopers LLP
Boston, Massachusetts
January 19, 2004






                                                                   Exhibit 23.2

                       CONSENT OF INDEPENDENT ACCOUNTANTS


We consent to the use of our report dated November 3, 2003 relating to the
combined financial statements of The Ecolochem Group, which report is
incorporated herein by reference, and to the reference to our firm under the
heading "experts" in the registration statement.

/s/ KPMG LLP
------------
KPMG LLP
Norfolk, Virginia
January 16, 2004






                            -------------------------

                         TESTA, HURWITZ & THIBEAULT, LLP
                            -------------------------
                                ATTORNEYS AT LAW

                                 125 High Street
                        Boston, Massachusetts 02110-2704
Office (617) 248-7000                                        Fax (617) 248-7100

                                             January 20, 2004

VIA EDGAR

Securities and Exchange Commission
Division of Corporate Finance
450 Fifth Street, N.W.
Judiciary Plaza
Washington, D.C.  20549
Attn:    Filing Desk

         Re:        Ionics, Incorporated  -  Registration Statement on Form S-3

Ladies and Gentlemen:

         On behalf of Ionics, Incorporated (the "Company"), transmitted herewith
for filing with the Securities and Exchange Commission (the "Commission")
pursuant to Regulation S-T is one (1) conformed copy of a Registration Statement
on Form S-3 (the "Registration Statement"), with exhibits, relating to the
offering by certain stockholders of the Company of an aggregate of 4,905,660
shares of common stock, par value $1.00 per share, of the Company.

         A filing fee of $11,953.62 has been paid prior to the Company's filing
of the Registration Statement by wire transfer to the Commission's account at
Mellon Bank.

         Pursuant to Rule 461 under the Securities Act of 1933 (the "Act"), the
Company may make a request for acceleration of the effective date of the above
referenced Registration Statement orally. As required by Rule 461, the Company
has authorized us to represent on their behalf that they are aware of their
obligations under the Act.

         If you should have any questions, or require any additional
information, please contact me at (617) 248-7292, Edwin C. Pease of this office
at (617) 248-7080 or Stephen Korn, the Company's Vice President and General
Counsel, at (617) 926-2500.

                                   Sincerely,

                                   /s/ Mark H. Burnett

                                   Mark H. Burnett
Enclosure