Exhibit 10.14.1

                          THIRD MODIFICATION AGREEMENT


     BY THIS THIRD MODIFICATION  AGREEMENT (the  "Agreement"),  made and entered
into  as of  the  13th  day  of  February,  2003,  WELLS  FARGO  BANK,  NATIONAL
ASSOCIATION,  as administrative agent (the "Administrative Agent") for the Banks
listed in the  hereinafter  defined  Credit  Agreement  (the "Banks") and as the
Issuing  Bank and the Swing Line Lender,  and KNIGHT  TRANSPORTATION,  INC.,  an
Arizona  corporation  (the  "Company")  and all present  and future  Significant
Subsidiaries of the Company (with the Company, the "Borrower"), in consideration
of  the  mutual   covenants   herein  contained  and  other  good  and  valuable
consideration,  the receipt  and  sufficiency  of which is hereby  acknowledged,
hereby confirm and agree as follows:

SECTION 1. RECITALS; ACKNOWLEDGEMENTS.

     1.1 The Borrower and the  Administrative  Agent and the Banks  entered into
that Credit  Agreement  dated April 6, 2001 (as amended  from time to time,  the
"Credit  Agreement")  to provide  financial  accommodations  to the  Borrower as
provided  therein.   The  Credit  Agreement  was  previously   amended  by  that
Modification  Agreement  dated as of June 5, 2001 and that  Second  Modification
Agreement dated as of November 19, 2001.

     1.2 Borrower and the  Administrative  Agent, with the consent of the Banks,
desire to modify the Credit Agreement as set forth herein.

     1.3 All  undefined  capitalized  terms used  herein  shall have the meaning
given them in the Credit Agreement.

SECTION 2. CREDIT AGREEMENT.

     2.1 The following  definitions  in Section 1.1 of the Credit  Agreement are
hereby amended to read as follows:

          "Letter of Credit Commitment" shall mean $10,000,000.00.

          "RLC Maturity Date" shall mean June 15, 2004.

     2.2 Section  2A.1(a) of the Credit  Agreement is hereby  amended to read as
follows:

          (a) Provided that the Borrower has satisfied the conditions  precedent
     contained in Section 2A.1(b) hereof, the Issuing Bank agrees,  from time to
     time,  to issue and/or renew Letters of Credit on behalf of the Borrower so
     long as (i) upon such  issuance  or  renewal,  an  issuance  fee is paid by
     Borrower  to the Issuing  Bank in an amount  equal to ninety  basis  points
     (0.9%)  per  annum  (computed  on the  basis of the  actual  number of days
     elapsed  in a year of 360  days) of the  amount of each  Letter of  Credit,
     which  issuance  fee  shall  be  allocated  pro  rata  among  the  Banks in
     accordance  with their  respective  Commitments,  (ii) the Letter of Credit
     Balance,  after giving effect to such Letter of Credit, will not exceed the
     Letter of Credit Commitment,  and (iii) the outstanding aggregate principal
     amount of all  Borrowings  made by all Banks  pursuant  to their  Revolving
<PAGE>
     Loan,  together  with the  Swing  Line  Balance  and the  Letter  of Credit
     Balance,  after giving effect to such Letter of Credit, will not exceed the
     Maximum RLC Commitment.

     2.3  Section  5.2 of the  Credit  Agreement  is hereby  amended  to read as
follows:

          SECTION 5.2  INSURANCE.  Maintain  adequate  insurance by  financially
     sound and  reputable  insurers of all  properties  of a  character  usually
     insured by companies engaged in the same or a similar business operating on
     a similar economic scale as the Borrower and its Subsidiaries  against loss
     or  damage   resulting  from  fire,   flood,   property   damage,   workers
     compensation,  or other risks insured  against by extended  coverage and of
     the kind  customarily  insured against by such  companies,  and maintain in
     full  force and  effect  public  liability  insurance  against  claims  for
     personal  injury,  death or property damage occurring upon, in, about or in
     connection with the use of any properties  occupied or controlled by it and
     its  Subsidiaries  in such  amounts as shall be customary  among  companies
     engaged  in the same or  similar  businesses  and  similarly  situated  and
     maintain  such other  insurance as may be required by law with  deductibles
     not in excess of  $2,000,000.00  per  occurrence  for  personal  injury and
     property damage liability, cargo liability and collision and comprehensive,
     and not in excess of $500,000.00 per occurrence for worker's compensation.

     2.4 Section  5.11(a) of the Credit  Agreement is hereby  amended to read as
follows:

          (a) Its Tangible Net Worth of not less than  $170,000,000.00  plus 50%
     of positive  net income and not reduced for any net losses plus 100% of any
     proceeds  from any equity stock  offering,  measured  quarterly  commencing
     December 31, 2002, with "Tangible Net Worth" defined as total stockholders'
     equity less its intangible assets, plus its Subordinated Debt.

     2.5 Section  6.2(d) of the Credit  Agreement  is hereby  amended to read as
follows:

          (d)  Capital  purchases  not  to  exceed   $65,000,000.00,   including
     operating leases, capital leases and debt.

     2.6  Section  6.6 of the  Credit  Agreement  is hereby  amended  to read as
follows:

          SECTION  6.6  ERISA  LIABILITIES.  Create  or  suffer  to exist  ERISA
     Liabilities   in  an   aggregate   amount   for  all  Plans  in  excess  of
     $2,500,000.00.

     2.7  Section  6.9 of the  Credit  Agreement  is hereby  amended  to read as
follows:

          SECTION 6.9  DIVIDEND,  DISTRIBUTIONS.  Declare or pay any dividend or
     distribution  in excess of fifty percent (50%) of Borrower's  net income in
     any fiscal year either in cash,  stock or any other  property on Borrower's
     stock now or  hereafter  outstanding,  nor redeem,  retire,  repurchase  in
     excess of $30,000,000.00 in any 12 month period effective as of the date of

                                      -2-
<PAGE>
     this Agreement,  or otherwise acquire any shares of any class of Borrower's
     stock now or hereafter outstanding.

     2.8  Exhibit  "F" of the  Credit  Agreement  is hereby  amended  to read as
attached hereto.

SECTION 3. OTHER MODIFICATIONS, RATIFICATIONS AND AGREEMENTS.

     3.1 All references to the Credit  Agreement in the other Loan Documents are
hereby amended to refer to the Credit Agreement as hereby amended.

     3.2 Borrower  hereby  reaffirms  to the Banks each of the  representations,
warranties,  covenants  and  agreements  of  Borrower  set  forth in the  Credit
Agreement,  with the same  force and  effect as if each were  separately  stated
herein and made as of the date hereof.

     3.3 Borrower hereby ratifies, reaffirms,  acknowledges, and agrees that the
Notes and the Credit  Agreement  represent  valid,  enforceable  and collectible
obligations  of  Borrower,  and that  there are no  existing  claims,  defenses,
personal or  otherwise,  or rights of setoff  whatsoever  with respect to any of
these documents or instruments.  Borrower  further  acknowledges  and represents
that no event has occurred and no condition  exists that,  after notice or lapse
of time, or both, would constitute a default under this Agreement,  the Notes or
the Credit Agreement.

     3.4 All  terms,  conditions  and  provisions  of the Credit  Agreement  are
continued in full force and effect and shall  remain  unaffected  and  unchanged
except as specifically amended hereby. The Credit Agreement,  as amended hereby,
is hereby  ratified  and  reaffirmed  by  Borrower,  and  Borrower  specifically
acknowledges the validity and enforceability thereof.

SECTION 4. GENERAL.

     4.1 This Agreement in no way acts as a release or  relinquishment  of those
rights  securing  payment  of  the  Loans.  Such  rights  are  hereby  ratified,
confirmed, renewed and extended by Borrower in all respects.

     4.2 The modifications  contained herein shall not be binding upon the Banks
until the Administrative Agent shall have received all of the following:

          (a) An original of this Agreement fully executed by the Borrower.

          (b) An executed consent from each Bank.

          (c) Such resolutions or authorizations and such other documents as the
     Administrative  Agent  may  require  relating  to the  existence  and  good
     standing of the Borrower and the  authority  of any person  executing  this
     Agreement or other documents on behalf of the Borrower.

     4.3 Borrower  shall  execute and deliver such  additional  documents and do
such  other acts as the Banks may  reasonably  require  to fully  implement  the
intent of this Agreement.

                                      -3-
<PAGE>
     4.4 Borrower shall pay all costs and expenses,  including,  but not limited
to,  reasonable   attorneys'  fees  incurred  by  the  Administrative  Agent  in
connection herewith, whether or not all of the conditions described in Paragraph
4.2 above are satisfied.  Banks, at their option,  but without any obligation to
do so,  may  advance  funds  to pay any such  costs  and  expenses  that are the
obligation of the Borrower,  and all such funds  advanced shall bear interest at
the highest rate provided in the Notes and shall be due and payable upon demand.

     4.5  Notwithstanding  anything to the contrary  contained  herein or in any
other instrument executed by Borrower, the Administrative Agent or the Banks, or
in any other action or conduct undertaken by Borrower,  the Administrative Agent
or the  Banks on or  before  the date  hereof,  the  agreements,  covenants  and
provisions  contained  herein shall  constitute  the only evidence of the Banks'
consent to modify the terms and provisions of the Credit Agreement. Accordingly,
no express or implied consent to any further modifications  involving any of the
matters set forth in this Agreement or otherwise shall be inferred or implied by
the  Banks'  consent to this  Agreement.  Further,  the  Banks'  consent to this
Agreement  shall not  constitute  a waiver  (either  express or  implied) of the
requirement that any further  modification of the Credit Agreement shall require
the express  written  consent of the Banks;  no such consent  (either express or
implied) has been given as of the date hereof.

     4.6 Time is hereby  declared  to be of the  essence  hereof  of the  Credit
Agreement, and Banks require, and Borrower agrees to, strict performance of each
and every covenant,  condition,  provision and agreement  hereof,  of the Credit
Agreement.

     4.7 This  Agreement  shall be binding upon,  and shall inure to the benefit
of, the parties hereto and their heirs, personal representatives, successors and
assigns.

     4.8 This  Agreement  is made for the sole  protection  and  benefit  of the
parties  hereto,  and no other  person or entity  shall have any right of action
hereon.

     4.9 This Agreement shall be governed by and construed according to the laws
of the State of Arizona.

     IN WITNESS  WHEREOF,  these  presents are executed as of the date indicated
above.

                                     WELLS FARGO BANK, NATIONAL ASSOCIATION


                                     By: /s/ Keri Tignini
                                         ---------------------------------------
                                     Name: Keri Tignini
                                           -------------------------------------
                                     Its: Assistant Vice President
                                          --------------------------------------

                                                            ADMINISTRATIVE AGENT

                                      -4-
<PAGE>
                                    KNIGHT TRANSPORTATION, INC.



                                    By: /s/ Tim Kohl
                                        ----------------------------------------
                                    Name: Tim Kohl
                                          --------------------------------------
                                    Its: CFO, Secretary
                                         ---------------------------------------


                                    QUAD-K LEASING, INC., an Arizona corporation



                                    By: /s/ Tim Kohl
                                        ----------------------------------------
                                    Name: Tim Kohl
                                          --------------------------------------
                                    Its: CFO, Secretary
                                         ---------------------------------------

                                                                        BORROWER

                                      -5-
<PAGE>
                              CONSENT OF THE BANKS


Re: Knight Transportation, Inc.

    The following:

     (a) is a Bank named in that Credit  Agreement  dated April 6, 2001  between
Knight Transportation, Inc., an Arizona corporation (the "Company"), all present
and future Significant Subsidiaries of the Company (the "Borrower"), Wells Fargo
Bank,  National  Association,   as  administrative  agent  for  the  Banks  (the
"Administrative Agent"), and the Banks; and

     (b) consents to that Third  Modification  Agreement dated February 13, 2003
entered into between the Borrower and the Administrative Agent.

                                     THE NORTHERN TRUST COMPANY, an Illinois
                                     banking corporation



                                     By: /s/ Eileen L. Sachanda
                                         ---------------------------------------
                                     Name: Eileen L. Sachanda
                                           -------------------------------------
                                     Its: Vice President
                                          --------------------------------------

                                                                          "Bank"
<PAGE>
                              CONSENT OF THE BANKS


Re: Knight Transportation, Inc.

    The following:

     (a) is a Bank named in that Credit  Agreement  dated April 6, 2001  between
Knight Transportation, Inc., an Arizona corporation (the "Company"), all present
and future Significant Subsidiaries of the Company (the "Borrower"), Wells Fargo
Bank,  National  Association,   as  administrative  agent  for  the  Banks  (the
"Administrative Agent"), and the Banks; and

     (b) consents to that Third  Modification  Agreement dated February 13, 2003
entered into between the Borrower and the Administrative Agent.

                                     WELLS FARGO BANK, NATIONAL ASSOCIATION



                                     By: /s/ Keri Tignini
                                         ---------------------------------------
                                     Name: Keri Tignini
                                           -------------------------------------
                                     Its: Assistant Vice President
                                          --------------------------------------

                                                                          "Bank"
<PAGE>
                                   EXHIBIT "F"

                        QUARTERLY COMPLIANCE CERTIFICATE
                            FOR FISCAL QUARTER ENDING
                             ________________, 20__




WELLS FARGO BANK, NATIONAL ASSOCIATION
As Administrative Agent for the Banks
100 West Washington
Phoenix, Arizona  85003

Attn: Arizona RCBO                                Date:_________________


Dear Ladies and Gentlemen:

     This Quarterly Compliance  Certificate refers to the Credit Agreement dated
as of April 6, 2001 (as it may  hereafter  be  amended,  modified,  extended  or
restated   from  time  to  time,   the   "Credit   Agreement"),   among   KNIGHT
TRANSPORTATION,  INC., an Arizona corporation,  and its Significant Subsidiaries
(collectively,  "Borrower"), the Banks named therein, WELLS FARGO BANK, NATIONAL
ASSOCIATION  as  Administrative  Agent for the  Banks,  and THE  NORTHERN  TRUST
COMPANY, an Illinois banking corporation,  as a Bank. Capitalized terms used and
not otherwise  defined herein shall have the meanings  assigned to such terms in
the Credit Agreement.

     Pursuant  to  Section  5.4 of the  Credit  Agreement,  the  undersigned,  a
Financial Officer of Borrower, certifies that:

     1. Enclosed are the required financial statements for the [quarter] [fiscal
year] (the "Reporting Period") ending for Borrower as required under Section 5.4
of the Credit Agreement.

     2. To the best of the  undersigned's  knowledge,  no "Event of  Default" or
Potential  Default  has  occurred  [or if so,  specifying  the nature and extent
thereof and any corrective actions taken or to be taken].

     3. As of the last day of the Reporting Period,  the computations below were
true and correct:
<PAGE>
I.   SECTION 5.11(a)   Tangible Net Worth
                       Initial Amount                            $170,000,000.00
                       +50% of positive net income               $______________
                       +100% of stock offering proceeds          $______________
                       since December 31, 2002
                       =Tangible Net Worth Limitation            $______________

                       Actual Tangible Net Worth:                $______________


II.  SECTION 5.11(b)   EBITDA Coverage Ratio
                       (calculated on a rolling 4 quarter basis)

Numerator:             Net Profit before Tax                     _______________
                       +Depreciation & Amortization Exp.         _______________
                       +Interest Expense (net of capitalized
                       interest expense)
                                                                 _______________
                       =EBITDA                                                 A
                                                                 ---------------

                       Divided by

Denominator:           Interest expense                          _______________
                       Current maturity of long-term
                       debt (prior period)                       _______________
                       +Current maturity of subordinated
                       debt (prior period)
                       +Dividends/distributions                  _______________
                       =Payment Requirement                                    B
                                                                 ---------------

                       Equals:                                               A/B
                                                                 ---------------

                       Minimum Required:                                   3.00X
                                                                 ---------------

III. SECTION 5.11(c)   Funded Debt to EBITDA Ratio
                       (calculated on a trailing 4 quarter basis)

Numerator:             Indebtedness                              _______________
                       +Letter of Credit Balance                 _______________
                       =Funded Debt                                            A
                                                                 ---------------

                       Divided by

Denominator:           EBITDA                                                  B
                                                                 ---------------

                       Equals:                                               A/B
                                                                 ---------------

                       Maximum Permitted:                                  1.50X
                                                                 ---------------

                                      -2-
<PAGE>
IV.  SECTION 5.11(d)   (i)  Net Income after Tax: actual         $______________
                                                   Requirement   =>        $1.00
                                                                 ---------------

                       (ii) Pre-Tax Profit: actual               $______________
                                                   Requirement   =>        $1.00
                                                                 ---------------

V.   SECTION 5.11(e)   Minimum Asset Coverage

Numerator:             Cash
                       +Net accounts receivable                  _______________
                       +real estate BV (<= $25,000,000.00)       _______________
                       +rolling stock NBV                        _______________
                       =Assets                                                 A
                                                                 ---------------

                       Divided by:

Denominator:           Accounts Payable                          _______________
                       +Outstanding Indebtedness
                       +Unfunded but committed Indebtedness      _______________
                       =Total                                                  B
                                                                 ---------------

                       Equals                                                A/B
                                                                 ---------------

                       Minimum Required                                   120.0%
                                                                 ---------------

                                     KNIGHT TRANSPORTATION, INC., an Arizona
                                     corporation


                                     By:
                                        ----------------------------------------
                                     Name:
                                          --------------------------------------
                                     Its:
                                         ---------------------------------------

                                      -3-