-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 AiR9tlqRT5FJvVDaseZ7W9zTyONgEvO9L1dihZZUAdllTn33Uy1ouMUXBBPCoFZ6
 EgN2KjjIdrUsbaDV6QlYpg==

<SEC-DOCUMENT>0001140361-03-001877.txt : 20030604
<SEC-HEADER>0001140361-03-001877.hdr.sgml : 20030604
<ACCEPTANCE-DATETIME>20030604172759
ACCESSION NUMBER:		0001140361-03-001877
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030602
FILED AS OF DATE:		20030604

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			KOHL TIMOTHY M
		CENTRAL INDEX KEY:			0001187222

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-24946
		FILM NUMBER:		03733083

	MAIL ADDRESS:	
		STREET 1:		5601 WEST BUCKEYE ROAD
		CITY:			PHOENIX
		STATE:			AZ
		ZIP:			85043

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			KNIGHT TRANSPORTATION INC
		CENTRAL INDEX KEY:			0000929452
		STANDARD INDUSTRIAL CLASSIFICATION:	TRUCKING (NO LOCAL) [4213]
		IRS NUMBER:				860649974
		STATE OF INCORPORATION:			AZ
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		5601 W BUCKEYE RD
		CITY:			PHOENIX
		STATE:			AZ
		ZIP:			85043
		BUSINESS PHONE:		6022692000

	MAIL ADDRESS:	
		STREET 1:		5601 W BUCKEYE RD
		CITY:			PHOENIX
		STATE:			AZ
		ZIP:			85043
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType>
<periodOfReport>2003-06-02</periodOfReport>
<notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0000929452</issuerCik>
        <issuerName>KNIGHT TRANSPORTATION INC</issuerName>
        <issuerTradingSymbol>KNGT</issuerTradingSymbol>
</issuer>
<reportingOwner>
<reportingOwnerId>
            <rptOwnerCik>0001187222</rptOwnerCik>
            <rptOwnerName>KOHL TIMOTHY M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector>
<isOfficer>1</isOfficer>
<isTenPercentOwner>0</isTenPercentOwner>
<isOther>0</isOther>
<officerTitle>Chief Financial Officer</officerTitle>
<otherText></otherText>
</reportingOwnerRelationship>
</reportingOwner>
<derivativeSecurity>
<securityTitle>
<value>Employee Stock Option (right to buy)</value>
</securityTitle>
<conversionOrExercisePrice>
<value>24.83</value>
</conversionOrExercisePrice>
<transactionDate>
<value>2003-06-02</value>
</transactionDate>
<transactionCoding>
<transactionFormType>4</transactionFormType>
<transactionCode>A</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionTimeliness>
<value></value>
</transactionTimeliness>
<transactionAmounts>
<transactionShares>
<value>10000</value>
</transactionShares>
<transactionValue>
<value>24.83</value>
</transactionValue>
<transactionAcquiredDisposedCode>
<value>A</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<exerciseDate>
<value>2006-05-20</value>
<footnoteId id="F1"/>
</exerciseDate>
<expirationDate>
<value>2013-05-20</value>
</expirationDate>
<underlyingSecurity>
<underlyingSecurityTitle>
<value>Common Stock</value>
</underlyingSecurityTitle>
<underlyingSecurityShares>
<value>10000</value>
</underlyingSecurityShares>
</underlyingSecurity>
<postTransactionAmounts>
<sharesOwnedFollowingTransaction>
<value>10000</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature>
<directOrIndirectOwnership>
<value>D</value>
</directOrIndirectOwnership>
<natureOfOwnership>
<value></value>
</natureOfOwnership>
</ownershipNature>
</derivativeSecurity>
<footnotes>
<footnote id="F1">The option vests in thirds beginning on May 20, 2006, and is exercisable in thirds beginning on that date.</footnote>
</footnotes>
<ownerSignature>
<signatureName>Timothy M. Kohl</signatureName>
<signatureDate>2003-06-04</signatureDate>
</ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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