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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 DJsoZqRKwOXmgEjTJG5xF8i1xZX8gbT6audVkwehJU+G1xP3xUY6+iohJFzF57wC
 l404+1QOoJO1fjSH1lJcDQ==

<SEC-DOCUMENT>0001179110-03-012517.txt : 20031212
<SEC-HEADER>0001179110-03-012517.hdr.sgml : 20031212
<ACCEPTANCE-DATETIME>20031212195447
ACCESSION NUMBER:		0001179110-03-012517
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20031210
FILED AS OF DATE:		20031212

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			YOUNGJOHNS ROBERT
		CENTRAL INDEX KEY:			0001220078

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-15086
		FILM NUMBER:		031052945

	BUSINESS ADDRESS:	
		STREET 1:		C/O SUN MICROSYSTEMS INC
		STREET 2:		4120 NETWORK CIRCLE M/S SCA12-202
		CITY:			SANTA CLARA
		STATE:			CA
		ZIP:			95054
		BUSINESS PHONE:		6509601300

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SUN MICROSYSTEMS INC
		CENTRAL INDEX KEY:			0000709519
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRONIC COMPUTERS [3571]
		IRS NUMBER:				942805249
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0630

	BUSINESS ADDRESS:	
		STREET 1:		4150 NETWORK CIRCLE
		CITY:			SANTA CLARA
		STATE:			CA
		ZIP:			95054
		BUSINESS PHONE:		6509601300

	MAIL ADDRESS:	
		STREET 1:		4150 NETWORK CIRCLE
		CITY:			SANTA CLARA
		STATE:			CA
		ZIP:			95054
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>
<periodOfReport>2003-12-10</periodOfReport>
<notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0000709519</issuerCik>
        <issuerName>SUN MICROSYSTEMS INC</issuerName>
        <issuerTradingSymbol>sunw</issuerTradingSymbol>
</issuer>
<reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001220078</rptOwnerCik>
            <rptOwnerName>YOUNGJOHNS ROBERT</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>4150 NETWORK CIRCLE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SANTA CLARA</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95054</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector>
<isOfficer>1</isOfficer>
<isTenPercentOwner>0</isTenPercentOwner>
<isOther>0</isOther>
<officerTitle>Executive Vice President</officerTitle>
<otherText></otherText>
</reportingOwnerRelationship>
</reportingOwner>
<nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value>
</securityTitle>
<transactionDate><value>2003-12-10</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>M</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>64000</value>
</transactionShares>
<transactionPricePerShare><value>3.0235</value>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>A</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>145203</value>
<footnoteId id="F1"></footnoteId>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</nonDerivativeTransaction>
</nonDerivativeTable>
<derivativeTable><derivativeTransaction><securityTitle><value>Employee Stock Option (Right to Buy)</value>
<footnoteId id="F2"></footnoteId>
</securityTitle>
<conversionOrExercisePrice><value>3.0235</value>
</conversionOrExercisePrice>
<transactionDate><value>2003-12-10</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>M</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>64000</value>
</transactionShares>
<transactionPricePerShare><value>0</value>
<footnoteId id="F4"></footnoteId>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<exerciseDate><value>1996-12-13</value>
<footnoteId id="F3"></footnoteId>
</exerciseDate>
<expirationDate><value>2003-12-13</value>
</expirationDate>
<underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value>
</underlyingSecurityTitle>
<underlyingSecurityShares><value>64000</value>
</underlyingSecurityShares>
</underlyingSecurity>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>0</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</derivativeTransaction>
</derivativeTable>
<footnotes><footnote id="F1">Reflects 5,930 Shares purchased under Sun Microsystems, Inc. 1990 Employee Stock Purchase plan on April 30, 2003.</footnote>
<footnote id="F2">Option granted on December 13, 1995 under Sun Microsystems, Inc. 1990 Long-Term Equity Incentive Plan.</footnote>
<footnote id="F3">Option is fully vested, having become exercisable in five equal annual installments commencing on December 13, 1996.</footnote>
<footnote id="F4">Price of Derivative Security will be determined at a future date.</footnote>
</footnotes>
<ownerSignature><signatureName>Robert Youngjohns</signatureName>
<signatureDate>2003-12-10</signatureDate>
</ownerSignature>
</ownershipDocument>

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