SECOND AMENDMENT TO
                               CREDIT AGREEMENT


      This SECOND  AMENDMENT TO CREDIT  AGREEMENT (this  "Agreement") is entered
into  as of  March  15,  1998,  by  and  between  Smithway  Motor  Xpress,  Inc.
("Borrower"),  Smithway  Motor Xpress Corp. as Guarantor (the  "Guarantor")  and
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, and a First  Amendment to Credit  Agreement dated
as of March  1,  1998 and the  parties  agree  that  certain  modifications  are
required to the Credit Agreement;

      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. The term  "Borrowing  Base"  appearing  in Section 9.1 hereof is hereby
deleted and in lieu thereof is inserted the following:

                  "Borrowing   Base"   means  an   amount  as  of  any  time  of
            determination  equal to the sum of: (a) eighty five percent (85%) of
            the  aggregate  amount  of the  Borrower's  then  existing  Eligible
            Accounts  , plus (b)  eighty  five  percent  (85%) of the  aggregate
            amount of East West's then existing  Eligible Accounts (which relate
            to  accounts  owed or owing to East  West),  plus (c)  seventy  five
            percent (75%) of the aggregate net book value of the  Borrower's and
            East  West's  unencumbered  trucks and  trailers.  Net book value is
            defined as the depreciated  book value of all of Borrower's and East
            West's  trucks  and  trailers  less  all   indebtedness   and  lease
            obligations relating thereto.

      3.  Concurrently  with the  execution of this  Amendment,  East West Motor
Express,  Inc.  ("East  West")  shall  execute a Guaranty,  the form of which is
attached hereto as Exhibit A.

      4.  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.


                                      1

<PAGE>



      5.  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.

      6. 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  Credit  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.

      7. 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.

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

      9. This Amendment was executed an 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  Agreement 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:  Executive Vice President

                                    Address Notice:
                                    P.O. Box 404
                                    Fort Dodge, Iowa 50501
                                    Attn:
                                    Facsimile:
                                    Tel:


                                      2

<PAGE>




                                    LASALLE NATIONAL BANK, as Lender

                                    By:     /s/ Bruce Linger
                                    Title:  Senior Vice President

                                    Address notices and Lending Office::
                                    135 S. LaSalle
                                    Chicago, Illinois 60603
                                    Attn: Mr. Bruce Linger
                                    Facsimile: (312) 904-6150
                                    Tel: (312) 904-8356

                           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 Credit  Agreement  dated as of  September  3,
1997,  as  amended,  and  hereby  consents  to the  Second  Amendment  to Credit
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:  Executive Vice President

                                    Address Notice:
                                    P.O. Box 404
                                    Fort Dodge, Iowa 50501
                                    Attn:
                                    Facsimile:
                                    Tel:



T:\40934\09397\2ndAmendment.wpd 03/16/98



                                      3

<PAGE>




                                   EXHIBIT A
                                   GUARANTY

            For  value  received  and in  consideration  of any and  all  loans,
advances or other financial  accommodations provided by LASALLE NATIONAL BANK, a
national banking association (referred to herein,  together with its successors,
assigns and  transferees,  as  "Lender") to SMITHWAY  MOTOR  XPRESS,  INC.  (the
"Borrower"),  including,  but not limited to, the revolving  loans  described in
that certain  Credit  Agreement  dated as of September  3, 1997,  as  thereafter
amended  from  time to time  (the  "Credit  Agreement")  entered  into by Lender
Borrower, and the undersigned.

            EAST  WEST  MOTOR   EXPRESS,   INC.,  a  South  Dakota   corporation
("Guarantor"),  derives a substantial  financial benefit from the Borrower,  and
hereby  unconditionally,  irrevocably and absolutely guarantees (a) the full and
prompt  payment,  when  due,  whether  at  maturity  or  earlier  by  reason  of
acceleration or otherwise, and at all times thereafter of all obligations of the
Borrower to Lender whenever and however created,  including, but not limited to,
obligations  of the  Borrower  with  respect  to payment  of the  principal  of,
prepayment charges (if any) and interest on the Loans (including interest on any
overdue principal and prepayment  charges,  if any, and, to the extent permitted
by law, on any overdue interest),  and all other amounts due to Lender under the
Credit  Agreement and the other Loan Documents  (this and all other  capitalized
terms used herein and not  otherwise  defined  shall have the meanings  ascribed
thereto in the Credit Agreement),  and (b) the prompt and faithful  performance,
discharge and observance of any of all other obligations, covenants, agreements,
conditions,  representations,  warranties,  indemnities  and  liabilities of the
Borrower  to be  performed,  discharged  or observed  by the  Borrower  under or
pursuant to any  agreement  of the  Borrower  with  Lender,  including,  but not
limited to the Credit Agreement,  the other Loan Documents,  and all agreements,
instruments  and  documents  executed or  delivered in  connection  therewith or
pursuant  thereto  (all  such  obligations  of the  Borrower  guaranteed  by the
Guarantor herein being hereinafter  called the  "Obligations").  If the Borrower
defaults in the  payment  when due of any of the  Obligations  (whether at their
stated maturity, by acceleration,  or otherwise), the Guarantor shall pay to the
unpaid holders of the Obligations (the "Holders"), on demand, the full amount of
such  Obligations  in immediately  available  funds at the place provided in the
relevant  document.  The  Guarantor  further  agrees  to pay (a) all  costs  and
expenses  including,   without  limitation,   all  court  costs  and  reasonable
attorneys'  fees  and  expenses  paid or  incurred  by each  of the  Holders  in
endeavoring  to  collect  all  or  any  part  of  the  Obligations  from,  or in
prosecuting  any action  against,  the  Borrower,  the  Guarantor,  or any other
guarantor of all or any part of the  Obligations  or in  endeavoring  to realize
upon any or all collateral (including,  but not limited to Collateral as defined
under any of the Credit Agreement or the other Loan  Documents),  and (b) to the
extent permitted by law, interest on the Obligations and such costs and expenses
at the applicable per annum rate set forth in the relevant document.

            The Guarantor hereby represents and warrants that:

            (a) The  Guarantor  has full  power,  authority  and legal  right to
execute this Guaranty.


<PAGE>



            (b) This Guaranty has been duly  authorized,  executed and delivered
by the Guarantor and  constitutes a legal,  valid and binding  obligation of the
Guarantor   enforceable   in   accordance   with  its  terms,   except  as  such
enforceability   may  be   limited   by   applicable   bankruptcy,   insolvency,
reorganization,   moratorium,  or  other  laws  relative  to  or  affecting  the
enforcement  of creditors'  rights  generally in effect from time to time and by
general principles of equity.

            (c) No  consent,  approval  or  authorization  of or filing with any
Governmental  Body or other  Person on the part of the  Guarantor is required in
connection   with  this   Guaranty,   except  such   consents,   approvals   and
authorizations, if any, as have been obtained.

            (d) The  execution,  delivery and  performance of this Guaranty will
not violate any provision of any  applicable  law or regulation or of any Order,
domestic or foreign,  or of the  articles or bylaws of the  Guarantor  or of any
securities  issued  by the  Guarantor  or of  any  mortgage,  indenture,  lease,
contract,  or loan  agreement to which the  Guarantor  is a party,  or any other
agreement,  instrument or undertaking to which the Guarantor is a party or which
purports to be binding upon the  Guarantor  or upon any of its assets,  and will
not result in the creation or imposition of any Lien on any of the assets of the
Guarantor  except as contemplated by this Guaranty,  the Credit  Agreement,  the
other Loan Documents or any other agreements between the Borrower and Lender.

            The Guarantor hereby waives notice of acceptance of this Guaranty by
any Holder,  of any action taken or omitted in reliance hereon or of any default
in the payment of any of the  Obligations or in the performance of any covenants
and agreements of the Borrower  contained in the Credit  Agreement or any of the
other Loan Documents or any other agreement between the Borrower and Lender, and
any diligence, presentment, demand, protest, dishonor or notice of any kind.

            This  Guaranty  constitutes  a present  and  continuing  guaranty of
payment and performance and not of collection of the  Obligations,  and shall be
absolute,  primary,  present and  unconditional;  and to the extent permitted by
applicable law, shall not be subject to any counterclaim,  setoff,  reduction or
defense  based upon any claim the Guarantor may have against the Borrower or any
other  Person and shall remain in full force and effect  without  regard to, and
shall not be  released,  discharged  or in any way  affected  or impaired by any
thing, event, happening,  matter,  circumstance or condition whatsoever (whether
or not the Guarantor shall have any knowledge or notice thereof or shall consent
thereto), including, without limitation:

                        (i) any amendment or other modification of or supplement
            to any provision of any  agreement or document  between the Borrower
            and Lender,  including,  but not limited to the Credit  Agreement or
            any other Loan  Document  or any  assignment  or  transfer  thereof,
            including  without  limitation any renewal or extension of the terms
            of  payment  of any of the  Loans or any other  indebtedness  of the
            Borrower to Lender or the granting of time in respect of any payment
            thereof,  or any furnishing or acceptance of security or any release
            of any security furnished or accepted for any of the Obligations;



<PAGE>



                        (ii) any waiver, consent,  extension,  granting of time,
            forbearance,  indulgence  or other  action or  inaction  under or in
            respect  of this  Guaranty,  the  Credit  Agreement,  the other Loan
            Documents,  or any other agreements  between the Borrower and Lender
            or any of the Loans or other  indebtedness of the Borrower to Lender
            or any  exercise or  non-exercise  of any right,  remedy or power in
            respect hereof or thereof;

                        (iii)  any   bankruptcy,   insolvency,   reorganization,
            arrangement,  readjustment,   composition,  liquidation  or  similar
            proceedings  with respect to the Borrower or any other Person except
            the Guarantor, or the properties or creditors of any of them;

                        (iv) the  occurrence  of any event of  default  or event
            which,  with the giving of notice or lapse of time,  or both,  would
            become an event of default,  as defined under the relevant document,
            or any invalidity or unenforceability of, or any  misrepresentation,
            irregularity  or other  defect in, the Credit  Agreement,  the other
            Loan  Documents,  or any other  agreement  between the  Borrower and
            Lender;

                        (v) any transfer of any assets to or from the  Guarantor
            or the  Borrower,  including  without  limitation  any  transfer  or
            purported transfer to the Guarantor or the Borrower from any Person,
            any  invalidity,  illegality  of, or inability to enforce,  any such
            transfer or purported  transfer,  any consolidation or merger of the
            Guarantor  or the  Borrower  with or into any other  corporation  or
            entity, or any change whatsoever in the objects,  capital structure,
            constitution  or business of the  Guarantor  or the  Borrower or any
            Affiliate or Subsidiary of the Guarantor or of the Borrower;

                        (vi)  any  failure  on the part of the  Borrower  or any
            other  Person to perform or comply  with any term of the Loans,  the
            Credit Agreement,  the other Loan Documents,  or any other agreement
            between the Borrower and Lender;

                        (vii) any suit or other action brought by the Guarantor,
            the Borrower or any other Person, or by any partner,  stockholder or
            creditor  of  any  of  such  Persons,  for  any  reason  whatsoever,
            including without limitation any suit or action in any way attacking
            or involving any issue, matter or thing in respect of the Loans, the
            Credit Agreement,  the other Loan Documents,  or any other agreement
            between the Borrower and Lender;

                        (viii)  any  lack or  limitation  of  status  or  power,
            incapacity or disability of the Borrower or of any officer, director
            or agent of the Borrower or any of its stockholders;

                        (ix) the cessation from any cause whatsoever (other than
            payment of the Obligations) of liability of the Borrower;



<PAGE>



                        (x) the  termination of, or release or compromise of the
            Credit Agreement,  the other Loan Documents,  or any other agreement
            between the Borrower  and Lender or any other  agreement or document
            executed or delivered in  connection  therewith or pursuant  thereto
            (other than as a result of payment of the Obligations);

                        (xi)  any  lack  or  limitation   of  the   genuineness,
            validity,  regularity or enforceability of the Credit Agreement, any
            Loan  Document,  any other  Loan  Document  or any  other  agreement
            between the Borrower  and Lender or any other  agreement or document
            executed or delivered in connection therewith or pursuant thereto;

                        (xii)  any  failure  by any of the  Holders  to take any
            steps to perfect or maintain any security interest in or Liens upon,
            or to preserve  their rights to any security or  collateral  for the
            Obligations;

                        (xiii)  any  election  by  any of  the  Holders,  in any
            proceeding  instituted  under  Chapter  11 of Title 11 of the United
            States Code (11 U.S.C. ss. 101 et seq.) (the "Bankruptcy  Code"), of
            the application of Section 1111(b)(2) of the Bankruptcy Code;

                        (xiv)  the  disallowance,   under  Section  502  of  the
            Bankruptcy Code, of all or any portion of any of the Holders' claims
            for repayment of the Obligations;

                        (xv) any  failure  to pursue or  enforce  any  rights or
            remedies  which  any of the  Holders  may  have  against  any  other
            guarantor of the Obligations, or any of them; or

                        (xvi)  any  other  thing,  event,   happening,   matter,
            circumstance or condition whatsoever,  not in any way limited to the
            foregoing,  which might  otherwise  constitute  a legal or equitable
            discharge or defense of a guarantor.

            Notwithstanding  anything to the contrary contained herein or in any
other agreement, document or instrument, the Guarantor hereby irrevocably waives
, until  such time as the  Obligations  have been  paid in full,  all  rights of
subrogation (whether such rights arise under common law, contract or federal law
(including,  without  limitation,  Section 509 of the  Bankruptcy  Code)) to the
claims  of the  Holders  against  the  Borrower,  and  waives  all  contractual,
statutory and common law rights of contribution, reimbursement,  indemnification
and similar rights and claims (as such term is defined in the  Bankruptcy  Code)
against the Borrower which may arise in connection with, or as a result of, this
Guaranty.

            The Guarantor  expressly waives any right it may have to require any
Person seeking  enforcement of its obligations  hereunder to (a) proceed against
the Borrower or any other  guarantor or Person,  (b) proceed  against or exhaust
any security, or (c) pursue any other remedy in the power


<PAGE>



of the Person  seeking such  enforcement.  The Holders from time to time may, at
their  election,  exercise  any  right  or  remedy  they may  have  against  the
Guarantor,  including,  without limitation, the right to foreclose upon any such
security by judicial or non-judicial  sale, without affecting or limiting in any
way  the  liability  of  the  Guarantor  hereunder,  except  to the  extent  the
Obligations  have been paid. The Guarantor waives any defense arising out of the
absence,  impairment  or loss of any  right of  reimbursement,  contribution  or
subrogation  or any other right or remedy of the Guarantor  against the Borrower
or any such security, whether resulting from such election by the Holders of the
Obligations or otherwise.

            The  Guarantor  agrees  that  its  obligations  hereunder  shall  be
automatically reinstated if and to the extent that for any reason any payment by
or on behalf of the Borrower or the  Guarantor is rescinded or must be otherwise
restored  by  any  Holder  of  any  Obligations,  whether  as a  result  of  any
proceedings in bankruptcy or reorganization or otherwise.  The Guarantor further
agrees that,  without  limiting the generality of the foregoing,  if an event of
default  shall have  occurred and be  continuing  and any Holder is prevented by
applicable  law from  exercising  any remedy under this Guaranty or under any of
the  Obligations,  such Holder shall be entitled to receive  from the  Guarantor
upon  demand  therefor,  the sums which would  otherwise  have been due from the
Borrower had such remedies been exercised.

            The Guarantor agrees that this Guaranty shall continue in full force
and effect and may not be terminated or otherwise revoked by the Guarantor until
the Obligations shall have been fully discharged.

            This  Guaranty  shall be  binding  upon the  Guarantor  and upon the
successors and assigns of the Guarantor and shall inure to the benefit of Lender
and  each  other  Holder  and  their  respective  successors  and  assigns;  all
references  herein  to the  Borrower  and to the  Guarantor  shall be  deemed to
include their respective  successors and permitted assigns,  including,  without
limitation,  a receiver,  trustee or debtor-in-possession of or for the Borrower
or the Guarantor.  All references to the singular shall be deemed to include the
plural where the context so requires.

            THIS GUARANTY SHALL BE  INTERPRETED,  AND THE RIGHTS AND LIABILITIES
OF THE PARTIES  HERETO  DETERMINED,  IN  ACCORDANCE  WITH THE INTERNAL  LAWS (AS
OPPOSED  TO  CONFLICTS  OF LAW  PROVISIONS)  AND THE  DECISIONS  OF THE STATE OF
ILLINOIS.

            THE GUARANTOR  HEREBY CONSENTS AND AGREES TO THE JURISDICTION OF ANY
STATE OR FEDERAL  COURT  SITTING IN THE COUNTY OF COOK,  STATE OF ILLINOIS,  AND
WAIVES ANY OBJECTION  BASED ON VENUE OR FORUM NON CONVENIENS WITH RESPECT TO ANY
ACTION  INSTITUTED   THEREIN,   AND  AGREES  THAT  ANY  DISPUTE  CONCERNING  THE
RELATIONSHIP BETWEEN LENDER OR HOLDERS OF OBLIGATIONS,  ON THE ONE HAND, AND THE
GUARANTOR,  ON THE OTHER HAND,  OR THE CONDUCT OF ANY PARTY IN  CONNECTION  WITH
THIS GUARANTY OR OTHERWISE SHALL BE HEARD ONLY IN THE COURTS DESCRIBED ABOVE.



<PAGE>


            Wherever   possible  each   provision  of  this  Guaranty  shall  be
interpreted  in such manner as to be effective and valid under  applicable  law,
but if any  provision of this  Guaranty  shall be prohibited by or invalid under
such law, such provision shall be ineffective to the extent of such  prohibition
or  invalidity  without  invalidating  the  remainder  of such  provision or the
remaining provisions of this Guaranty.

            THE GUARANTOR HEREBY WAIVES ANY RIGHT TO TRIAL BY JURY OF ANY CLAIM,
DEMAND,  ACTION OR CAUSE OF ACTION (i) ARISING  UNDER THIS GUARANTY OR ANY OTHER
INSTRUMENT,  DOCUMENT OR AGREEMENT EXECUTED OR DELIVERED IN CONNECTION  HEREWITH
OR (ii) IN ANY WAY  CONNECTED  WITH OR RELATED OR  INCIDENTAL TO THE DEALINGS OF
THE GUARANTOR IN RESPECT OF THIS GUARANTY OR ANY OTHER  INSTRUMENT,  DOCUMENT OR
AGREEMENT  EXECUTED OR  DELIVERED  IN  CONNECTION  HEREWITH OR THE  TRANSACTIONS
RELATED  HERETO,  IN EACH CASE WHETHER NOW EXISTING OR  HEREAFTER  ARISING,  AND
WHETHER  SOUNDING IN CONTRACT OR TORT OR OTHERWISE.  THE GUARANTOR HEREBY AGREES
AND  CONSENTS  THAT ANY SUCH CLAIM,  DEMAND,  ACTION OR CAUSE OF ACTION SHALL BE
DECIDED BY COURT  TRIAL  WITHOUT A JURY AND THAT ANY PARTY MAY FILE AN  ORIGINAL
COUNTERPART OR A COPY OF THIS GUARANTY WITH ANY COURT AS WRITTEN EVIDENCE OF THE
CONSENT OF THE GUARANTOR TO THE WAIVER OF ITS RIGHT TO TRIAL BY JURY.

            IN WITNESS  WHEREOF,  this  Guaranty  has been duly  executed by the
Guarantor as of the 15th day of March, 1998.


                        EAST WEST MOTOR EXPRESS, INC., a South Dakota
                        corporation



                        By:         /s/ William G. Smith

                        Title:      Director

<PAGE>