As filed with the Securities and Exchange Commission on May 30, 2003
                                                      Registration No. 333-72377

                             WASHINGTON, D.C. 20549


                         POST-EFFECTIVE AMENDMENT NO. 1
                                    FORM S-8
                          REGISTRATION STATEMENT UNDER
                           THE SECURITIES ACT OF 1933


                           KNIGHT TRANSPORTATION, INC.
             (Exact name of Registrant as specified in its charter)

                 ARIZONA                                 86-0649974
                 (State)                    (I.R.S. Employer Identification No.)

           5601 W. BUCKEYE RD.
            PHOENIX, ARIZONA                               85043
(Address of Principal Executive Offices)                 (Zip Code)

                                STOCK OPTION PLAN
                            (Full title of the plan)


                                  With copy to:
      Kevin P. Knight                                 James E. Brophy, III, Esq.
  Chief Executive Officer                             Ryley Carlock & Applewhite
Knight Transportation, Inc.                                   Suite 1200
  5601 West Buckeye Road                               One North Central Avenue
  Phoenix, Arizona 85043                                Phoenix, Arizona 85004
      (602) 269-2000                                       (602) 258-7701
            (Name, address and telephone number of agent for service)


                            DEREGISTRATION OF SHARES

     As  originally  filed on February 16,  1999,  this  Registration  Statement
registered 1,500,000 shares of the Common Stock of Knight  Transportation,  Inc.
(the  "Company")  which had been approved for issuance  under the Company's 1998
Amended and Restated  Stock Option Plan (the "1998  Plan").  The Company now has
adopted a new plan, the 2003 Knight Transportation,  Inc. Stock Option Plan (the
"2003 Plan") to which shares  remaining  available for grant under the 1998 Plan
may be used  for the  purpose  of new  grants.  As of May 21,  2003,  a total of
1,576,896  shares of the Company's  Common Stock were subject to outstanding but
unexercised  option  grants,  and a total of 471,187  shares were  reserved  for
future stock grants under the 1998 Plan,  after giving  effect to the  Company's
three-for-two  stock  splits  and the 2002  Amendment  to the 1998  Plan,  which
increased  the  number of shares  reserved  for  issuance.  This  post-effective
Amendment is being filed to deregister 471,187  previously  registered shares of
the  Company's  stock  reserved  for  issuance  under the 1998 Plan that are not
subject to outstanding but unexercised option grants.

     A new Form S-8  Registration  Statement  will be  filed by the  Company  to
register shares issuable under the 2003 Plan.



     THE REGISTRANT. Pursuant to the requirements of the Securities Act of 1933,
the Registrant certifies that it has reasonable grounds to believe that it meets
all of the  requirements  for  filing  on  Form  S-8 and has  duly  caused  this
Post-Effective  Amendment  No.  1 to the  Form S-8  Registration  Statement  No.
333-72377  to be  signed  on its  behalf  by  the  undersigned,  thereunto  duly
authorized,  in the City of Phoenix,  State of Arizona, on this 29th day of May,

                                       KNIGHT TRANSPORTATION, INC.,
                                       an Arizona corporation

                                       By /s/ Kevin P. Knight
                                          Kevin P. Knight, Chairman of the Board
                                          and Chief Executive Officer

     Pursuant  to  the   requirements  of  the  Securities  Act  of  1933,  this
Post-Effective  Amendment No. 1 to the Form S-8 Registration  Statement has been
signed by the following persons in the capacities and on the date indicated.

SIGNATURE AND TITLE                                                    DATE
-------------------                                                    ----

/s/ Kevin P. Knight                                                 May 29, 2003
Kevin P. Knight, Chairman of the Board,
Chief Executive Officer, Director

/s/ Gary J. Knight                                                  May 29, 2003
Gary J. Knight, President, Director

/s/ Keith T. Knight                                                 May 29, 2003
Keith T. Knight,
Executive Vice President, Director

/s/ Timothy M. Kohl                                                 May 29, 2003
Timothy M. Kohl, Director, Chief Financial
Officer and Secretary

/s/ Donald A. Bliss                                                 May 29, 2003
Donald A. Bliss, Director

                                                                    May 29, 2003
Randy Knight, Director

                                                                    May 29, 2003
G.D. Madden, Director

                                                                    May 29, 2003
Matt Salmon, Director

/s/ Mark Scudder                                                    May 29, 2003
Mark Scudder, Director