March 28, 2003




Smithway Motor Xpress, Inc.
2031 Quail Avenue
Fort Dodge, Iowa 50501

And

East West Motor Express, Inc.
1170 JB drive
Black Hawk, South Dakota 57718

Re:  Fourth Amendment to Amended and Restated Loan and Security
     Agreement

Gentlemen:

     Smithway Motor Xpress, Inc., an Iowa corporation ("Smithway Inc.") and East
West Motor Express,  Inc., a South Dakota  corporation  ("East West")  (Smithway
Inc. and East West each a  "Borrower"  and  collectively  the  "Borrowers")  and
LaSalle Bank National Association,  a national banking association ("Bank") have
entered into that certain Amended and Restated Loan and Security Agreement dated
December  28, 2001 (the  "Security  Agreement").  From time to time  thereafter,
Borrowers and Bank may have executed various amendments (each an "Amendment" and
collectively the "Amendments") to the Security Agreement (the Security Agreement
and  the  Amendments   hereinafter  are  referred  to,   collectively,   as  the
"Agreement").  Borrowers  and Bank now desire to further  amend the Agreement as
provided herein, subject to the terms and conditions hereinafter set forth.

     NOW,  THEREFORE,  in  consideration of the foregoing  recitals,  the mutual
covenants  and   agreements  set  forth  herein  and  other  good  and  valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
parties hereto hereby agree as follows:

     1. The Agreement hereby is amended as follows:

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Smithway Motor Xpress, Inc.
March 28, 2003
Page 2

     (a)  Section  (10) of the  Agreement  is  deleted in its  entirety  and the
following is substituted in its place:

          (10) TERMINATION; AUTOMATIC RENEWAL.

               THIS  AGREEMENT  SHALL BE IN EFFECT UNTIL UPON  EXECUTION OF THIS
               AMENDMENT UNTIL DECEMBER 31, 2003 (THE "ORIGINAL TERM") AND SHALL
               AUTOMATICALLY  RENEW ITSELF FROM MONTH TO MONTH  THEREAFTER (EACH
               SUCH  ONE-MONTH  RENEWAL  BEING  REFERRED TO HEREIN AS A "RENEWAL
               TERM") unless (A) THE DUE DATE OF THE  LIABILITIES IS ACCELERATED
               PURSUANT TO SECTION 16 HEREOF; OR (B) A BORROWER OR LENDER ELECTS
               TO TERMINATE THIS AGREEMENT AT THE END OF THE ORIGINAL TERM OR AT
               THE END OF ANY  RENEWAL  TERM BY GIVING THE OTHER  PARTY  WRITTEN
               NOTICE OF SUCH  ELECTION AT LEAST  FIFTEEN (15) DAYS PRIOR TO THE
               END OF THE  ORIGINAL  TERM OR THE THEN  CURRENT  RENEWAL  TERM IN
               WHICH CASE BORROWERS  SHALL PAY ALL OF THE LIABILITIES IN FULL ON
               THE LAST DAY OF SUCH TERM. If one or more of the events specified
               in clauses (a) and (b) occurs, then (i) Lender shall not make any
               additional  Loans on or after the date  identified as the date on
               which the Liabilities  are to be repaid;  and (ii) this Agreement
               shall  terminate on the date  thereafter that the Liabilities are
               paid in full.  At such time as  Borrowers  have repaid all of the
               Liabilities  and this Agreement has  terminated,  Borrowers shall
               deliver to Lender a release,  in form and substance  satisfactory
               to Lender,  of all  obligations and liabilities of Lender and its
               officers, directors, employees, agents, parents, subsidiaries and
               affiliates to such Borrowers,  and if Borrowers are obtaining new
               financing  from  another  lender,  Borrowers  shall  deliver such
               lender's   indemnification  of  Lender,  in  form  and  substance
               satisfactory  to Lender,  for checks which Lender has credited to
               such Borrower's  account,  but which  subsequently are dishonored
               for any reason or for automatic  clearinghouse  or wire transfers
               not yet posted to such Borrower's account.


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Smithway Motor Xpress, Inc.
March 28, 2003
Page 3

     (b)  Subsection  14 (a) of the Agreement is deleted in its entirety and the
following is substituted in its place:

          (a)  Tangible Net Worth

               The Consolidated Group's Tangible Net Worth shall not at any time
               be less than the Minimum  Tangible Net Worth;  "Minimum  Tangible
               Net Worth" being  defined for purposes of this  subsection as (i)
               $13,000,000.00 at all times from January 1, 2003 through December
               31, 2003; and (ii)  thereafter,  from the last day of each Fiscal
               Year of the Consolidated  Group through the day prior to the last
               day  of  each   immediately   succeeding   Fiscal   Year  of  the
               Consolidated  Group,  the Minimum  Tangible  Net Worth during the
               immediately  preceding period plus  $1,000,000.00;  and "Tangible
               Net Worth" being  defined for purposes of this  subsection as the
               Consolidated  Group's  shareholders'  equity (including  retained
               earnings)  less  the  book  value  of all  intangible  assets  as
               determined solely by Lender on a consistent basis plus the amount
               of any LIFO reserve plus the amount of any debt  subordinated  to
               Lender,  all as determined  under generally  accepted  accounting
               principles  applied  on a basis  consistent  with  the  financial
               statement dated December 31, 2002 except as set forth herein;

     2. This Amendment  shall not become  effective  until fully executed by all
parties hereto.

     3.  Except  as  expressly  amended  hereby  and by any  other  supplemental
documents or instruments  executed by either party hereto in order to effectuate
the transactions contemplated hereby, the Agreement and Exhibit A thereto hereby
are  ratified and  confirmed by the parties  hereto and remain in full force and
effect in accordance with the terms thereof.

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Smithway Motor Xpress, Inc.
March 28, 2003
Page 4


                               LASALLE BANK NATIONAL ASSOCIATION

                               By  /s/ John Mostofi
                                  -----------------------------
                               Title    Sr VP
                                     --------------------------

ACKNOWLEDGED AND AGREED TO
this 28th day of March, 2003:

SMITHWAY MOTOR XPRESS, INC.

By  /s/ William G. Smith
   -----------------------------
     William G. Smith

Title  President

EAST WEST MOTOR EXPRESS, INC.

By  /s/ William G. Smith
   -----------------------------
     William G. Smith

Title  President

Consented and agreed to by the
following guarantor(s) of the
obligations of Smithway Motor
Xpress, Inc. and East West
Motor Express, Inc. to
LaSalle Bank National Association.

SMSD Acquisition Corp.

By: /s/ G. Larry Owens
   -----------------------------
     G. Larry Owens

Title: Vice President

Date:  March 28, 2003

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Smithway Motor Xpress, Inc.
March 28, 2003
Page 5


Smithway Motor Xpress Corp.

By: /s/ G. Larry Owens
   -----------------------------
     G. Larry Owens

Title: Vice President

Date:  March 28, 2003