SEVENTH AMENDMENT TO
                                CREDIT AGREEMENT


     This SEVENTH  AMENDMENT TO CREDIT  AGREEMENT (this  "Amendment") is entered
into  as of  August  25,  2000,  by and  between  Smithway  Motor  Xpress,  Inc.
("Borrower"),  Smithway  Motor Xpress Corp. as Guarantor (the  "Guarantor")  and
LaSalle Bank National  Association,  formerly known as LaSalle National Bank, as
Lender (the "Lender").

                              W I T N E S S E T H:

     WHEREAS,  the Borrower and the  Guarantor  entered into a Credit  Agreement
dated as of September 3, 1997, a First Amendment to Credit Agreement dated as of
March 1, 1998,  a Second  Amendment  to Credit  Agreement  dated as of March 15,
1998,  a Third  Amendment  to Credit  Agreement  dated as of October 30, 1998, a
Fourth  Amendment  to Credit  Agreement  dated as of August  20,  1999,  a Fifth
Amendment  to  Credit  Agreement  dated  as of  December  17,  1999  and a Sixth
Amendment to Credit Agreement dated as of July 1, 2000 (collectively referred to
as the "Agreement"); and

     WHEREAS, the Borrower has requested certain  modifications to the Agreement
and the Lender is willing to do so on the following terms and conditions; and

     NOW, THEREFORE,  in consideration of the mutual agreements,  provisions and
covenants contained herein, the parties agree as follows:

     1. Unless otherwise stated herein,  all of the capitalized  terms contained
in this document shall have the same meanings as contained in the Agreement.

     2.  Section  1.1(b) of the  Agreement  is  deleted in its  entirety  and is
replaced with the following:

               (b)  Letters of Credit.  Subject to the terms and  conditions  of
          this Agreement,  in addition to advances under the Revolving Loan, the
          Revolving Commitment may be utilized for the issuance by the Lender of
          letters of credit  (each a "Letter of  Credit").  In  determining  the
          amount of  outstanding  Letters of Credit,  the  maximum  amount  then
          undrawn  under each Letter of Credit plus any drawings  which have not
          been  reimbursed  to the Lender will be considered  outstanding.  Each
          Letter of Credit  shall  expire  not later than one (1) year after the
          date of its  issuance  and at  least  thirty  (30)  days  prior to the
          Revolving  Termination  Date in  effect  from  time to time.  For each
          requested  Letter of Credit, a Borrower shall give the Lender not less
          than five (5) Business  Days' prior written  notice by delivery to the
          Lender of a duly completed and executed application for such Letter of
          Credit on the form  prescribed  or required  by the Lender,  which the
          Lender may accept or reject in its sole  discretion.  At no time shall
          the total outstanding Letters of Credit exceed $6,000,000.




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               The Borrower shall be irrevocably and unconditionally  obligated,
          forthwith without presentment, demand, protest or other formalities of
          any kind,  to reimburse  the Lender for any amounts paid by the Lender
          under any Letter of Credit. The Borrower hereby authorizes and directs
          the Lender,  at the Lender's  option,  to make a Revolving Loan in the
          amount of any payment made by the Lender with respect to any Letter of
          Credit.  All amounts  paid by the Lender with respect to any Letter of
          Credit  that  are not  immediately  repaid  by the  Borrower  with the
          proceeds of a Revolving  Loan or otherwise  shall bear interest at the
          interest rate then applicable to Revolving Loans, calculated using the
          Prime Rate and the Applicable Margin in effect.

     3. This Amendment will become  effective upon the execution and delivery of
this Amendment by each of Borrower, Guarantor, East West and SMSD.

     4. Borrower shall pay 50% of the legal fees incurred in connection with the
preparation  of this  Amendment and the documents  and  instruments  referred to
herein,  and shall pay 100% of all out of pocket costs incurred by the Lender or
its attorneys.

     5. Borrower expressly acknowledges and agrees that all collateral, security
interests,  liens, pledges, and mortgages heretofore,  under this Amendment,  or
hereafter granted to Lender,  including,  without  limitation,  such collateral,
security  interests,  liens,  pledges and mortgages granted under the Agreement,
and all  other  supplements  to the  Agreement,  extend  to and cover all of the
obligations of Borrower to Lender,  now existing or hereafter arising including,
without limitation,  those arising in connection with the Agreement,  as amended
by this  Amendment,  upon the terms set forth in such  agreements,  all of which
security  interests,   liens,   pledges,  and  mortgages  are  hereby  ratified,
reaffirmed, confirmed and approved.

     6. Borrower represents and warrants to Lender that (i) it has all necessary
power and  authority  to execute  and  deliver  this  Amendment  and perform its
obligations hereunder, (ii) this Amendment and the Agreement, as amended hereby,
constitute  the  legal,  valid  and  binding  obligations  of  Borrower  and are
enforceable  against  Borrower in  accordance  with their  terms,  and (iii) all
representations  and  warranties  of Borrower  contained  in the  Agreement,  as
amended,  and all other  agreements,  instruments  and other  writings  relating
thereto, are true, correct and complete as of the date hereof.

     7. The parties hereto  acknowledge  and agree that the terms and provisions
of this Amendment amend,  add to and constitute a part of the Agreement.  Except
as  expressly  modified and amended by the terms of this  Amendment,  all of the
other terms and  conditions  of the  Agreement,  as amended,  and all  documents
executed in connection  therewith or referred to or incorporated  therein remain
in full  force and effect and are hereby  ratified,  reaffirmed,  confirmed  and
approved.


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     8. If there is an express  conflict between the terms of this Amendment and
the terms of the Agreement, or any of the other agreements or documents executed
in connection  therewith or referred to or  incorporated  therein,  the terms of
this Amendment shall govern and control.

     9. This  Amendment  may be  executed in one or more  counterparts,  each of
which shall be deemed to be an original.

     10. This  Amendment  was  executed and  delivered in Chicago,  Illinois and
shall be governed by and  construed in  accordance  with the  internal  laws (as
opposed to conflicts of law provisions) of the State of Illinois.

     IN WITNESS WHEREOF, this Seventh Amendment has been duly executed as of the
day and year specified at the beginning hereof.

                                      SMITHWAY MOTOR XPRESS, INC., as Borrower

                                      By:  /s/ G. Larry Owens
                                      Title:  Exec. V.P.

                                      Address Notice:
                                      P.O. Box 404
                                      Fort Dodge, Iowa 50501
                                      Attn: G. Larry Owens
                                      Facsimile: (515) 576-3304
                                      Tel: (515) 576-7418


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                                       SMITHWAY MOTOR XPRESS CORP., as Guarantor

                                       By:  /s/  G. Larry Owens
                                       Title:  Exec. V.P.

                                       Address Notice:
                                       P.O. Box 404
                                       Fort Dodge, Iowa 50501
                                       Attn: G. Larry Owens
                                       Facsimile: (515) 576-3304
                                       Tel: (515) 576-7418

                                       LASALLE BANK NATIONAL ASSOCIATION,
                                       as Lender

                                       By:  /s/ David A. Chaika
                                       Title:  AVP

                                       Address notices and Lending Office:
                                       135 South LaSalle Street
                                       Chicago, Illinois 60603
                                       Attn: Mr. David A. Chaika
                                       Facsimile: (312) 904-6150

                            CONSENT AND RATIFICATION

     The undersigned, pursuant to that certain Guaranty dated as of September 3,
1997,  is a guarantor  of all of the  obligations  of the Borrower to the Lender
under the terms of the Agreement and hereby consents to the Seventh Amendment to
the Agreement.  Guarantor  hereby  reaffirms and ratifies his guaranty as if the
same were fully set forth herein.

                                       SMITHWAY MOTOR XPRESS CORP., as Guarantor

                                       By:  /s/ G. Larry Owens
                                       Title:  Exec. V.P.

     The  undersigned,  pursuant to that certain  Guaranty dated as of March 15,
1998,  is a guarantor  of all of the  obligations  of the Borrower to the Lender
under the terms of the Agreement

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and hereby consents to the Seventh Amendment to the Agreement.  Guarantor hereby
reaffirms and ratifies his guaranty as if the same were fully set forth herein.

                                     EAST WEST MOTOR EXPRESS, INC., as Guarantor


                                     By:  /s/ G. Larry Owens
                                     Title:  Exec. V.P.


     The undersigned, pursuant to that certain Guaranty dated as of December 17,
1999,  is a guarantor  of all of the  obligations  of the Borrower to the Lender
under the terms of the Agreement and hereby consents to the Seventh Amendment to
the Agreement.  Guarantor  hereby  reaffirms and ratifies his guaranty as if the
same were fully set forth herein.

                                     SMSD ACQUISITION CORP., a South Dakota
                                     corporation, as Guarantor


                                     By:  /s/ G. Larry Owens
                                     Title:  Exec. V.P.


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