-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 O8nQ00PUK7Y2nCdQN3tuw5AV+U+xCv1dwfm2Ng6czbxDiVjGg8/raNWcqzn/zta7
 bIEnKLqexFgB+++LZbVlEg==

<SEC-DOCUMENT>0001179110-03-007864.txt : 20030924
<SEC-HEADER>0001179110-03-007864.hdr.sgml : 20030924
<ACCEPTANCE-DATETIME>20030924151715
ACCESSION NUMBER:		0001179110-03-007864
CONFORMED SUBMISSION TYPE:	4/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030818
FILED AS OF DATE:		20030924

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SANDERSON BILL M
		CENTRAL INDEX KEY:			0001228358

	FILING VALUES:
		FORM TYPE:		4/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-10389
		FILM NUMBER:		03907837

	BUSINESS ADDRESS:	
		STREET 1:		C/O WESTERN GAS RESOURCES INC
		STREET 2:		1099 18TH STREET STE 1200
		CITY:			DENVER
		STATE:			CO
		ZIP:			80202
		BUSINESS PHONE:		3034525603

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			WESTERN GAS RESOURCES INC
		CENTRAL INDEX KEY:			0000856716
		STANDARD INDUSTRIAL CLASSIFICATION:	NATURAL GAS TRANSMISSION [4922]
		IRS NUMBER:				841127613
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1099 18TH STREET, SUITE 1200
		CITY:			DENVER
		STATE:			CO
		ZIP:			80202-1955
		BUSINESS PHONE:		303 452 5603

	MAIL ADDRESS:	
		STREET 1:		1099 18TH STREET, SUITE 1200
		CITY:			DENVER
		STATE:			CO
		ZIP:			80202-1955
</SEC-HEADER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4/A -
<TEXT>
<XML>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4/A</documentType>
<periodOfReport>2003-08-18</periodOfReport>
<dateOfOriginalSubmission>2003-08-20</dateOfOriginalSubmission>
<notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0000856716</issuerCik>
        <issuerName>WESTERN GAS RESOURCES INC</issuerName>
        <issuerTradingSymbol>WGR</issuerTradingSymbol>
</issuer>
<reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001228358</rptOwnerCik>
            <rptOwnerName>SANDERSON BILL M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1099 18TH STREET, SUITE 1200</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>DENVER</rptOwnerCity>
            <rptOwnerState>CO</rptOwnerState>
            <rptOwnerZipCode>80202</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector>
<isOfficer>0</isOfficer>
<isTenPercentOwner>0</isTenPercentOwner>
<isOther>0</isOther>
<officerTitle></officerTitle>
<otherText></otherText>
</reportingOwnerRelationship>
</reportingOwner>
<nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value>
</securityTitle>
<transactionDate><value>2003-08-18</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>S</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>138990</value>
</transactionShares>
<transactionPricePerShare><value>38.4444</value>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>383335</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>I</value>
</directOrIndirectOwnership>
<natureOfOwnership><value>See footnote</value>
<footnoteId id="F1"></footnoteId>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeTransaction>
<nonDerivativeTransaction><securityTitle><value>Common Stock</value>
</securityTitle>
<transactionDate><value>2003-08-18</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>S</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>16682</value>
</transactionShares>
<transactionPricePerShare><value>38.5667</value>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>366653</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>I</value>
</directOrIndirectOwnership>
<natureOfOwnership><value>See footnote</value>
<footnoteId id="F2"></footnoteId>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeTransaction>
<nonDerivativeTransaction><securityTitle><value>Common Stock</value>
</securityTitle>
<transactionDate><value>2003-08-18</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>S</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>38100</value>
</transactionShares>
<transactionPricePerShare><value>38.4844</value>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>328553</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>I</value>
</directOrIndirectOwnership>
<natureOfOwnership><value>See footnote</value>
<footnoteId id="F3"></footnoteId>
<footnoteId id="F4"></footnoteId>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeTransaction>
</nonDerivativeTable>
<derivativeTable></derivativeTable>
<footnotes><footnote id="F1">138,890 shares sold by Cedar Assets Trust.  Following the transaction, Reporting Person's shares held as follows: 125,337 shares held by Reporting Person and spouse as joint tenants, 30,000 shares held in Reporting Person's IRA; 210,252 held by Cedar Assets Trust, the beneficiaries of which are children of the Reporting Person; 200 shares held by the Sanderson Family Foundation, of which the Reporting Person and his spouse are the directors; 16,682 held by the Sanderson Stock Trust, of which the Reporting Person's spouse is the trustee; and 864 held by Reporting Person's spouse.</footnote>
<footnote id="F2">16,682 shares sold by Sanderson Stock Trust, of which Reporting Person's spouse is the trustee.  Following the transaction, Reporting Person's shares held as follows: 125,337 shares held by Reporting Person and spouse as joint tenants, 30,000 shares held in Reporting Person's IRA; 210,252 held by Cedar Assets Trust, the beneficiaries of which are children of the Reporting Person; 200 shares held by the Sanderson Family Foundation, of which the Reporting Person and his spouse are the directors; and 864 held by Reporting Person's spouse.</footnote>
<footnote id="F3">38,100 shares sold by Reporting Person and his spouse, as joint tenants.  Following the transaction, Reporting Person's shares held as follows: 87,237 shares held by Reporting Person and spouse as joint tenants, 30,000 shares held in Reporting Person's IRA; 210,252 held by Cedar Assets Trust, the beneficiaries of which are children of the Reporting Person; 200 shares held by the Sanderson Family Foundation, of which the Reporting Person and his spouse are the directors; and 864 held by Reporting Person's spouse.</footnote>
<footnote id="F4">Amendment filed to correct the number of shares sold by Reporting Person and to correct the amount of securities beneficially owned by Reporting Person following each reported transaction.</footnote>
</footnotes>
<ownerSignature><signatureName>/s/ Bill M. Sanderson</signatureName>
<signatureDate>2003-09-19</signatureDate>
</ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----