Pricing Supplement No. 7

Pricing Supplement No. 8
Dated March 10, 2004
(to Prospectus dated November 28, 2001
and Prospectus Supplement
dated December 5, 2001)

Merck & Co., Inc.
Medium-Term Notes, Series E
Floating Rate Notes

Underwriter and Principal

Morgan Stanley & Co. Incorporated


Trade Date:

March 10, 2004
Settlement Date
(Original Issue Date):

March 15, 2004

Stated Maturity:

February 12, 2044
Interest Rate Basis:

3-month LIBOR

Minus 45 basis points
Initial Interest Rate: 3-month LIBOR, determined as if the original issue date were an interest reset date, minus the spread

Interest Reset Dates: Quarterly, on the 12th day of each February, May, August and November, commencing May 12, 2004

Interest Payment Dates: February 12, May 12, August 12 and November 12 of each year, commencing May 12, 2004

Issue Price:

100.00% of the principal amount, plus accrued interest from February 12, 2004

Underwriter’s Discount:

1.00% of the principal amount
Net Proceeds to Merck:

99.00% of the principal amount, plus accrued interest from February 12, 2004

Calculation Agent:

U.S. Bank Trust National Association
CUSIP: 58933NAY5

Optional Repayment Dates: The notes will be repayable at the option of the holder on at least 30 day notice on the following optional repayment dates and at the following repayment prices:


Optional Repayment Date

Repayment Price

  February 12, 2005 98.00%

  February 12, 2006 98.00%

  February 12, 2007 98.00%

  February 12, 2008 98.00%

  February 12, 2009 98.00%

  February 12, 2010 99.00%

  February 12, 2011 99.00%

  February 12, 2012 99.00%

  February 12, 2013 99.00%

  February 12, 2014 99.00%

  February 12, 2015 and each third
anniversary thereafter to maturity

Optional Redemption: The notes may be redeemed at any time, at the option of Merck, in whole or in part, in amounts of $1,000 or any multiple of $1,000, at the following redemption prices, if redeemed during the following 12-month periods:


Redemption Period

Redemption Price

  February 12, 2034 through February 11, 2035 105.00%

  February 12, 2035 through February 11, 2036 104.50%

  February 12, 2036 through February 11, 2037 104.00%

  February 12, 2037 through February 11, 2038 103.50%

  February 12, 2038 through February 11, 2039 103.00%

  February 12, 2039 through February 11, 2040 102.50%

  February 12, 2040 through February 11, 2041 102.00%

  February 12, 2041 through February 11, 2042 101.50%

  February 12, 2042 through February 11, 2043 101.00%

  February 12, 2043 through February 11, 2044 100.50%

        On February 9, 2004, we issued $25,000,000 aggregate principal amount of our floating rate notes due February 12, 2044. The notes offered hereby and our outstanding floating rate notes due February 12, 2044 will have the same terms, will trade as a single class of freely tradable notes and will form a single series and class for all purposes under the indenture. The total aggregate principal amount outstanding of our floating rate notes due February 12, 2044 will be $50,000,000.

Notes Used as Qualified Replacement Property:

Prospective investors seeking to treat the notes as “qualified replacement property” for purposes of Section 1042 of the Internal Revenue Code of 1986, as amended (the “Code”), should be aware that Section 1042 requires the issuer to meet certain requirements in order for the notes to constitute qualified replacement property. In general, qualified replacement property is a security issued by a domestic “operating corporation” that did not, for the taxable year preceding the taxable year in which such security was purchased, have “passive investment income” in excess of 25 percent of the gross receipts of such corporation for such preceding taxable year (the “Passive Income Test”). A corporation will be considered an “operating corporation” if at the time the securities are purchased or before the end of the replacement period, as defined in Section 1042 of the Code, more than 50 percent of its assets are used in the active conduct of a trade or business. For these purposes, where the issuing corporation is in control of one or more corporations or such issuing corporation is controlled by one or more other corporations, all such corporations are treated as one corporation (the “Affiliated Group”) for the purposes of computing the amount of passive investment income for purposes of Section 1042. Merck believes that it is an “operating corporation” and that less than 25 percent of its Affiliated Group’s gross receipts is passive investment income for the taxable year ending December 31, 2003. In making this determination, Merck has made certain assumptions and used procedures which it believes are reasonable. However, the calculation and characterization of certain types of income (as active or passive investment income) in certain of the Affiliated Group’s finance and insurance companies is not entirely clear as there are no Treasury regulations or rulings promulgated by the Internal Revenue Service (the “IRS”) that explain the calculation and characterization of such income in circumstances similar to those of Merck’s Affiliated Group. Even if such categories of income were treated as passive investment income, Merck believes that the Affiliated Group’s passive investment income did not exceed more than 25 percent of the Affiliated Group’s gross receipts for the taxable year ending December 31, 2003. No assurance can be given as to whether Merck will continue to meet the Passive Income Test. It is, in addition, possible that the IRS may disagree with the manner in which Merck has calculated the Affiliated Group’s gross receipts (including the characterization thereof) and passive investment income and the conclusions reached herein. Investors that treat the notes as “qualified replacement property” are subject to special rules regarding their basis and holding period in the notes. Investors should consult their own tax advisors about the operation of the rules relating to qualified replacement property in their particular circumstances.