SECOND AMENDMENT TO
                            ASSET PURCHASE AGREEMENT


         This Second Amendment to Asset Purchase  Agreement (the "Amendment") is
made as of December 12, 1996, by and among Smithway Motor Xpress,  Inc., an Iowa
corporation  ("Smithway");  Smithway Motor Xpress Corp.,  a Nevada  corporation;
Marquardt Transportation, Inc., a South Dakota corporation ("Seller"); and Ralph
and  Lucille  Marquardt,  individual  residents  of  Yankton,  South  Dakota and
Seller's sole Shareholders (together, the "Shareholders").

                                    RECITALS

         The  parties  previously  entered  into  that  certain  Asset  Purchase
Agreement dated October 4, 1996, (the "Main Agreement") and a First Amendment to
Asset Purchase Agreement dated October 24, 1996 (the "First Amendment"). Certain
events have  transpired  since the  execution  of the Main  Agreement  and First
Amendment that the parties wish to reflect in writing.

         NOW,  THEREFORE,  in  consideration  of the foregoing  recitals and the
mutual covenants, representations, and warranties herein contained, and upon the
terms and conditions hereinafter set forth, the parties hereto agree as follows:

        1.  Amendment of Main Agreement and First  Amendment.  The provisions of
this Amendment shall supplement and amend the Main Agreement and First Amendment
as specifically  stated herein.  Except as stated herein, the Main Agreement and
First Amendment shall continue in full force and effect.  Capitalized terms used
herein and not otherwise  defined herein shall have the meanings ascribed in the
Main Agreement and First Amendment.

        2.  California  Lease.  On the  date  hereof,  Seller  shall  assign  to
Smithway,  and Smithway  shall accept from Seller,  an  assignment  of the lease
attached as Exhibit G to the Main  Agreement  (the  "California  Lease") and all
rights to payments from  subtenants,  and Smithway shall agree to pay,  perform,
and discharge all obligations under the California Lease from and after the date
hereof.  Rent payable by Smithway under the  California  Lease shall be prorated
from  October 26,  1996,  to November 1, 1996,  resulting  in a $967  payment by
Smithway to Seller.  For the additional soil samplings that were required in the
Stockton Phase I  Environmental  Assessment,  Seller and Smithway each shall pay
half of the $1,226.50 fee assessed for the soil  samplings.  Smithway  shall pay
the  entire  amount  due for the  additional  soil  samplings  and $613  will be
deducted from the Escrowed Funds, as hereinafter defined, released to Seller.

     3. Inventory. Pursuant to Section 2.6 of the Main Agreement Smithway was to
pay cost for parts, tires, supplies, and general inventory (not to include items
out-dated and  non-usable to Smithway).  Pursuant to the First  Amendment,  such
amount  was  subject to  adjustment  from a  physical  count of such  inventory.
Smithway has conducted an inspection and tagging of the inventory and determined
the amount that is not out-dated and non-usable. At closing, Smithway  deposited


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in escrow  with  Davenport,  Evans,  Hurwitz & Smith,  L.P.   ("Escrow  Agent"),
the amount of $369,313 (the  "Escrowed  Funds"),  including  $179,663.12  as  an
estimated  amount for the parts and tire inventory.  The parties hereby agree to
deductions  of  $40,975  and  $51,686  for the   parts   and   tire   inventory,
respectively,  from the $179,663.12  estimated amount. The parties further agree
that $92,661 shall be deducted from the remaining Escrowed Funds and returned to
Smithway to effect the parts and tire inventory adjustment previously described.

        4.  Goodwill  Payment.  Smithway  heretofore  has paid  Seller  $448,000
pursuant to Section 2.9 of the Main Agreement. The Main Agreement provided for a
payment of $200,000 on April 25, 1997,  adjusted  upward or downward  based upon
the number of  drivers  then  based in  Yankton.  The  parties  hereby  agree to
eliminate  such  adjustment  and alter the  payment  schedule  to  provide  that
Smithway  shall pay Seller  $100,000  on the date  hereof and  deliver  Seller a
promissory  note due April 25,  1997,  in the amount of  $100,000.  Accordingly,
Section 2.9 of the Main  Agreement is deleted in its entirety and replaced  with
new Section 2.9, which shall read as follows:

                  2.9      Business.  Smithway shall pay Seller $648,000 for the
                           goodwill associated with the Business,  including the
                           value of ongoing shipper,  Driver, and other business
                           relationships.  Payment shall be made as follows: (a)
                           at Closing,  Smithway paid $448,000 to Marquardt, and
                           (b) on December 12, 1996,  Smithway  shall deliver to
                           Seller  a  check  in the  amount  of  $100,000  and a
                           promissory  note due April 25, 1997, in the amount of
                           $100,000.

        5.  Inspections and Return of Marquardt  Equipment.  Pursuant to Section
2.13 of the  Main  Agreement,  the  parties  conducted  certain  Inspections  of
Tractors,  Leased Tractors,  Trailers,  and Leased Trailers.  The parties hereby
agree that the Adjustment Amount is $33,286,  representing  $8,271 for brake and
tire wear to the  Tractors,  Leased  Tractors,  Trailers,  and  Leased  Trailers
purchased or assumed by Smithway and $25,015 for mileage penalties. Accordingly,
the sum of $33,286  shall be deducted  from the  Escrowed  Funds and returned to
Smithway in settlement of the Adjustment  Amount.  In addition,  Smithway hereby
agrees to  relinquish  its claim for  $13,025,  in body damage to the  Tractors,
Leased Tractors,  Trailers, and Leased Trailers purchased or assumed by Smithway
and, in exchange, Seller and Shareholders hereby accept all Nonacquired Tractors
and  Trailers  returned or to be returned to them by Smithway "as is" and waive,
release,  and  relinquish  all  rights  to a claim  for  damages  regarding  the
condition of such returned tractors and trailers.

        6.  Damage to Tractor  Struck in Yankton  Yard.  Smithway  shall pay the
agreed  cost of parts  and  labor  incurred  in  connection  with  damage to the
driver's  side of the tractor  struck in the Yankton  yard  ($2,094)  and Seller
shall pay the agreed cost of parts and labor incurred for damage to the opposite
side of the  tractor  ($1,681),  such  agreed  costs  being  those  depicted  in
parentheses.  The parties  agree that $2,094 shall be paid to Seller by Smithway
and Seller shall be obligated to pay any repair costs on such tractor  struck in
the Yankton yard.

        7. Repair Expenses.  Smithway shall pay the repair and towing expense on
tractor  #314 in the  amount  of  $1,412.  Seller  shall  pay the $654 in repair
expense for the tractor  driver  shaft that broke while under a Marquardt  load.
Smithway  previously  paid  this  amount  and $654  shall be  deducted  from the
Escrowed Funds and returned to Smithway.

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     8. Headache Racks.  Smithway shall forgive any  deficiencies in the number,
or portions  thereof,  of headache racks delivered by Seller and no amount shall
be deducted from any sums paid to Seller. Any uncounted portions of the headache
racks that are in the  possession  of Smithway  on the date hereof  shall be the
property of Smithway.

        9.  Equipment  Rental and Return.  Smithway  shall pay Seller the sum of
$8,000 for (a) use of Nonacquired  Trucks beyond the 30-day allowed period,  (b)
use of Nonacquired  Trucks that were taken from the Yankton or Stockton terminal
after being  brought to such  terminal,  and (c) any late return of the priority
tractors  to Yankton.  Seller  agrees that all  Nonacquired  Tractors  have been
returned to Seller.  Seller shall pick up seven dry vans from Fort Dodge,  Iowa,
Smithway shall not be required to return such vans to Seller, and Smithway shall
deliver on or prior to December 19, 1996 the one remaining dry van to Yankton or
Sioux City, as instructed by Ralph Marquardt.

       10.  Consulting  Services of Ralph Marquardt.  Smithway shall continue to
pay Ralph  Marquardt the  consulting fee as provided in Section 2.12 of the Main
Agreement  and shall  rent an office  for Ralph  Marquardt  in  Yankton  through
January  31,  1997.  Except for the  purposes  and at the times  provided in the
Yankton lease  entered into between the parties and the auction  provided in the
First  Amendment,  Ralph Marquardt  shall not enter the Yankton  terminal or the
premises on which it is located,  and shall  instruct John  Marquardt to refrain
from entering the Yankton terminal and premises.

     11.  Forklifts.  Smithway shall not purchase either of the forklifts at the
Yankton  terminal.  Smithway  previously paid Seller $7,500 for one forklift and
such  amount  shall be  deducted  from the  Escrowed  Funds and be  returned  to
Smithway.

     12.  Yankton  Terminal Rent. The first sentence of Section 2.10 of the Main
Agreement  shall be deleted in its  entirety  and  replaced  with the  following
sentence, which shall read as follows:

                  2.10     Yankton Lease. Smithway shall lease the Property from
                           Seller for four years at a monthly  rental of $2,000,
                           triple net, pursuant to the Lease; provided, however,
                           the Yankton  terminal rent payable by Smithway  shall
                           be  prorated  from  October  26,  1996 to November 1,
                           1996,  resulting  in a $387  payment by  Smithway  to
                           Seller.

The  remaining  language  of Section  2.10 of the Main  Agreement  shall read as
stated in the Main Agreement.

       13. Phone Service at Yankton Terminal.  Seller and Shareholders  agree to
continue the present  phone  service,  with the existing  phone  number,  at the
Yankton terminal through January 31, 1997, at which time the phone number may be
transferred  as Ralph  Marquardt  desires.  Although  the phone  service  may be
switched to Smithway's  account  prior to January 31, 1997,  the phone number or
any  other  aspects  of the  phone  service  will not be  modified  by Seller or
Shareholders in any manner. Seller and Shareholders acknowledge that the harm to
Smithway's  business would be  irreparable  if there were a disruption,  for any
period  of  time,  in  the  phone service at the Yankton terminal by reason of a

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modification,  cancellation, or change in the phone  service  or  number  before
Smithway is ready to change the phone service and number on January 31, 1997.

       14.  Services of Oren Post.  Through January 31, 1997, Oren Post shall be
permitted to assist Mike Kabeiseman for a reasonable amount of time in gathering
documents  necessary  in the  preparation  of  Seller's  and  Shareholders'  tax
returns; provided,  however, that only Mike Kabeiseman or his staff may call Mr.
Post and such calls and the  assistance of Mr. Post shall not interfere with his
services to Smithway.

       15.        Miscellaneous.

                 a.        Smithway  shall  pay  Seller  $37,736  for  the  G.E.
                           Capital title,  California inventory,  and California
                           air  compressor  and battery  charger not  previously
                           paid for by Smithway.  Such payment  shall be made by
                           the release of such amount of the  Escrowed  Funds to
                           Seller.

                 b.        Revenue  shall be  split  on the  load  from the East
                           Coast to Carson,  Nevada for which Smithway equipment
                           was  used  for a  portion  of the  load.  Seller  has
                           previously collected all of the revenue from the load
                           and shall pay  Smithway  $1,080 by  deducting  $1,080
                           from the Escrowed  Funds and returning such amount to
                           Smithway.

                 c.        Seller shall pay Smithway  $17,015  for  one  missing
                           trailer.  Such amount shall be paid by  deducting  it
                           from  the Escrowed Funds and returning such amount to
                           Smithway.

                 d.        Seller  shall  pay  the  cargo  claim  relating  to a
                           particular Seller  transported load on which a $2,270
                           cargo claim was incurred,  and any other cargo claims
                           on Seller  transported loads. The sum of $2,270 shall
                           be deducted  from the Escrowed  Funds and returned to
                           Smithway.

                 e.        Seller owes approximately $5,500 in quarterly  safety
                           bonuses that were due  to  drivers  for  the  quarter
                           ended  September  30,  1996.  Smithway shall pay such
                           amount  to the drivers,  and $5,500 shall be deducted
                           from  the  Escrowed  Funds  and returned to Smithway.
                           Drivers are not entitled to safety  bonuses unless in
                           the  employ  of  Seller  or  Smithway at December 31,
                           1996.  Oren  Post shall determine if any safety bonus
                           amount is not payable to a driver because such driver
                           left Seller or Smithway before December 31, 1996, and
                           any  such  amount shall be paid to Seller by Smithway
                           within  ten  days  of presentation to Smithway by Mr.
                           Post.

         16. Direction to Escrow Agent. The parties hereby agree that the amount
of the Escrowed Fund is $132,000. The parties further agree that under the terms
of this  Amendment,  such amount  shall be  distributed  $11,395 to Smithway and
$120,605 to Seller as set forth in the attached schedule, incorporated herein by
this  reference.  The parties  hereby  direct  Escrow  Agent to  distribute  the
Escrowed Fund in accordance with this Section 16 immediately.

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       17.  Counterparts.  This  Amendment  can be  executed  in any  number  of
counterparts  and any party  hereto may  execute any such  counterpart,  each of
which when executed and  delivered  shall be deemed to be an original and all of
which  counterparts  taken  together  shall  constitute  but one  and  the  same
instrument.  This Amendment  shall become binding when one or more  counterparts
taken together  shall have been executed and delivered by the parties.  It shall
not be necessary in making proof of this Amendment or any counterpart  hereof to
produce or account for any of the other counterparts.

         IN  WITNESS  WHEREOF,  the  parties  hereto  have  duly  executed  this
Amendment on the date first written.

MARQUARDT TRANSPORTATION, INC.,                     SMITHWAY MOTOR XPRESS, INC.,
a South Dakota corporation                                   an Iowa corporation

By:                                                 By:
         Ralph Marquardt, President                  William G. Smith, President


                                                    SMITHWAY MOTOR XPRESS CORP.,
Ralph Marquardt, Individually                        a Nevada corporation


Lucille Marquardt, Individually                     By:
                                                     William G. Smith, President


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                                    SCHEDULE

Remaining Escrowed Funds:                                             $ 132,000
                                                                      =========

Deductions from payments to Seller:
         Half of California soil samplings                                 (613)
         Adjustment for parts inventory                                 (40,975)
         Adjustment for tire inventory                                  (51,686)
         Adjustment Amount for brake and tire wear                       (8,271)
         Adjustment Amount for mileage penalty                          (25,015)
         Repair expense on tractor drive shaft under
                  Marquardt load                                           (654)
         Returned forklift at Yankton terminal                           (7,500)
         Revenue share on load from East Coast to
                  Carson, Nevada                                         (1,080)
         One missing trailer                                            (17,015)
         Seller cargo claim                                              (2,270)
         Quarterly safety bonus                                          (5,500)
                                                                   ------------
Total deductions to Seller:                                           $(160,579)

Balance to Seller after application of remaining Escrowed Funds:     $  (28,579)
                                                                    ===========

Credits to Seller:
         California lease prorate                                           967
         Goodwill payment                                               100,000
         Equipment rental and return                                      8,000
         Damage to driver side of tractor struck
                  in Yankton yard                                         2,094
         Yankton lease prorate                                              387
         G.E. Title, California inventory, and California
                  air compressor and battery charger                     37,736
                                                                     ----------
Total credits to Seller:                                             $  149,184
                                                                     ----------

Total Amount Owed Seller by Smithway:                                $  120,605
                                                                     ==========



Amount from remaining Escrowed Funds to be Released to Seller:       $  120,605

Amount from remaining Escrowed Funds to be Released to Smithway:    $    11,395


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