-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 BkqapZogNF3N8XyvFXSMMbsZs3/9hTGG6Zsybf+LuahtZo/ctZYhQePbMKPytaer
 v0U0EBNZsH0Dq8IRoTgkEw==

<SEC-DOCUMENT>0001179110-03-002571.txt : 20030701
<SEC-HEADER>0001179110-03-002571.hdr.sgml : 20030701
<ACCEPTANCE-DATETIME>20030701094411
ACCESSION NUMBER:		0001179110-03-002571
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030630
FILED AS OF DATE:		20030701

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			TIERNO RALPH T III
		CENTRAL INDEX KEY:			0001190035

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-11443
		FILM NUMBER:		03766449

	BUSINESS ADDRESS:	
		STREET 1:		C/O STEWART & STEVENSON SERVICES INC
		STREET 2:		P O BOX 1637
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77251-1637
		BUSINESS PHONE:		7138687606

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			STEWART & STEVENSON SERVICES INC
		CENTRAL INDEX KEY:			0000094328
		STANDARD INDUSTRIAL CLASSIFICATION:	ENGINES & TURBINES [3510]
		IRS NUMBER:				741051605
		STATE OF INCORPORATION:			TX
		FISCAL YEAR END:			0131

	BUSINESS ADDRESS:	
		STREET 1:		2707 N LOOP W
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77008
		BUSINESS PHONE:		7138687700

	MAIL ADDRESS:	
		STREET 1:		P O BOX 1637
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77251-1637
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType>
<periodOfReport>2003-06-30</periodOfReport>
<notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0000094328</issuerCik>
        <issuerName>STEWART &amp; STEVENSON SERVICES INC</issuerName>
        <issuerTradingSymbol>SVC</issuerTradingSymbol>
</issuer>
<reportingOwner><reportingOwnerId>
            <rptOwnerCik>0001190035</rptOwnerCik>
            <rptOwnerName>TIERNO RALPH T III</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector>
<isOfficer>1</isOfficer>
<isTenPercentOwner>0</isTenPercentOwner>
<isOther>0</isOther>
<officerTitle>Vice President</officerTitle>
<otherText></otherText>
</reportingOwnerRelationship>
</reportingOwner>
<nonDerivativeSecurity><securityTitle><value>Common Stock</value>
</securityTitle>
<transactionDate><value>2003-06-30</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>M</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>5000</value>
</transactionShares>
<transactionValue><value>9.5625</value>
</transactionValue>
<transactionAcquiredDisposedCode><value>A</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>5000</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
<natureOfOwnership><value></value>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeSecurity>
<nonDerivativeSecurity><securityTitle><value>Common Stock</value>
</securityTitle>
<transactionDate><value>2003-06-30</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>S</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>4700</value>
</transactionShares>
<transactionValue><value>15.50</value>
</transactionValue>
<transactionAcquiredDisposedCode><value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>300</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
<natureOfOwnership><value></value>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeSecurity>
<nonDerivativeSecurity><securityTitle><value>Common Stock</value>
</securityTitle>
<transactionDate><value>2003-06-30</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>S</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>300</value>
</transactionShares>
<transactionValue><value>15.60</value>
</transactionValue>
<transactionAcquiredDisposedCode><value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>0</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
<natureOfOwnership><value></value>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeSecurity>
<derivativeSecurity><securityTitle><value>Employee Stock Option (right to buy)</value>
</securityTitle>
<conversionOrExercisePrice><value>9.5625</value>
</conversionOrExercisePrice>
<transactionDate><value>2003-06-30</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>M</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>5000</value>
</transactionShares>
<transactionValue><value>0</value>
</transactionValue>
<transactionAcquiredDisposedCode><value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<exerciseDate><value>2001-03-16</value>
<footnoteId id="F1"></footnoteId>
</exerciseDate>
<expirationDate><value>2010-03-16</value>
</expirationDate>
<underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value>
</underlyingSecurityTitle>
<underlyingSecurityShares><value>5000</value>
</underlyingSecurityShares>
</underlyingSecurity>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>5000</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
<natureOfOwnership><value></value>
</natureOfOwnership>
</ownershipNature>
</derivativeSecurity>
<footnotes><footnote id="F1">The stock option becomes exercisable in four equal annual installments commencing 3/16/01.</footnote>
</footnotes>
<ownerSignature><signatureName>Ralph T. Tierno III, By:  Rita Schaulat, attorney-in-fact</signatureName>
<signatureDate>2003-06-30</signatureDate>
</ownerSignature>
</ownershipDocument>

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