-----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,
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 6psJ6CEygCe8Y0+68EI9kQ==

<SEC-DOCUMENT>0001104659-03-015753.txt : 20030728
<SEC-HEADER>0001104659-03-015753.hdr.sgml : 20030728
<ACCEPTANCE-DATETIME>20030725193559
ACCESSION NUMBER:		0001104659-03-015753
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030723
FILED AS OF DATE:		20030728

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MCCABE EUGENE G
		CENTRAL INDEX KEY:			0001242781

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-15086
		FILM NUMBER:		03804478

	MAIL ADDRESS:	
		STREET 1:		4150 NETWORK CIRCLE
		CITY:			SANTA CLARA
		STATE:			CA
		ZIP:			95054

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>a4.xml
<DESCRIPTION>4
<TEXT>
<XML>
<?xml version="1.0" encoding="utf-8"?>
<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType>
  <periodOfReport>2003-07-23</periodOfReport>
  <notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0000709519</issuerCik>
        <issuerName>SUN MICROSYSTEMS INC</issuerName>
        <issuerTradingSymbol>SUNW</issuerTradingSymbol>
  </issuer>
  <reportingOwner>
    <reportingOwnerId>
            <rptOwnerCik>0001242781</rptOwnerCik>
            <rptOwnerName>MCCABE EUGENE G</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>Senior Vice President</officerTitle>
    </reportingOwnerRelationship>
  </reportingOwner>
  <nonDerivativeSecurity>
    <securityTitle>
      <value>Common Stock</value>
    </securityTitle>
    <transactionDate>
      <value>1988-08-08</value>
      <footnoteId id="F1"/>
    </transactionDate>
    <transactionCoding>
      <transactionFormType>4</transactionFormType>
      <transactionCode>J</transactionCode>
      <equitySwapInvolved>0</equitySwapInvolved>
      <footnoteId id="F2"/>
    </transactionCoding>
    <transactionTimeliness>
      <value/>
    </transactionTimeliness>
    <transactionAmounts>
      <transactionShares>
        <value>0</value>
      </transactionShares>
      <transactionValue>
        <value>0</value>
      </transactionValue>
      <transactionAcquiredDisposedCode>
        <value>A</value>
      </transactionAcquiredDisposedCode>
    </transactionAmounts>
    <postTransactionAmounts>
      <sharesOwnedFollowingTransaction>
        <value>29068</value>
        <footnoteId id="F3"/>
      </sharesOwnedFollowingTransaction>
    </postTransactionAmounts>
    <ownershipNature>
      <directOrIndirectOwnership>
        <value>D</value>
      </directOrIndirectOwnership>
    </ownershipNature>
  </nonDerivativeSecurity>
  <derivativeSecurity>
    <securityTitle>
      <value>Option (right to buy)</value>
    </securityTitle>
    <conversionOrExercisePrice>
      <value>3.85</value>
    </conversionOrExercisePrice>
    <transactionDate>
      <value>2003-07-23</value>
    </transactionDate>
    <transactionCoding>
      <transactionFormType>4</transactionFormType>
      <transactionCode>A</transactionCode>
      <equitySwapInvolved>0</equitySwapInvolved>
    </transactionCoding>
    <transactionTimeliness>
      <value/>
    </transactionTimeliness>
    <transactionAmounts>
      <transactionShares>
        <value>360000</value>
      </transactionShares>
      <transactionValue>
        <value>0</value>
        <footnoteId id="F5"/>
      </transactionValue>
      <transactionAcquiredDisposedCode>
        <value>A</value>
      </transactionAcquiredDisposedCode>
    </transactionAmounts>
    <exerciseDate>
      <value>2004-07-23</value>
      <footnoteId id="F4"/>
    </exerciseDate>
    <expirationDate>
      <value>2013-07-23</value>
    </expirationDate>
    <underlyingSecurity>
      <underlyingSecurityTitle>
        <value>Common Stock</value>
      </underlyingSecurityTitle>
      <underlyingSecurityShares>
        <value>360000</value>
      </underlyingSecurityShares>
    </underlyingSecurity>
    <postTransactionAmounts>
      <sharesOwnedFollowingTransaction>
        <value>360000</value>
      </sharesOwnedFollowingTransaction>
    </postTransactionAmounts>
    <ownershipNature>
      <directOrIndirectOwnership>
        <value>D</value>
      </directOrIndirectOwnership>
    </ownershipNature>
  </derivativeSecurity>
  <footnotes>
    <footnote id="F1">In the Section 16 Electronic Reporting Frequently Asked Questions released by the SEC on May 1, 2003, the SEC has designated "08/08/1988" as a "dummy date" until the electronic system is modified. This line reports end of period direct holdings for this reporting person, and 08/08/1988 is not a transaction date related to these securities.</footnote>
    <footnote id="F2">There has been no transaction in the direct holdings for this reporting person.</footnote>
    <footnote id="F3">Reflects 6,036 Shares purchased under Sun Microsystems, Inc. 1990 Employee Stock Purchase Plan on April 30, 2003.</footnote>
    <footnote id="F4">The option was granted under Sun Microsystems, Inc. 1990 Long Term Equity Incentive Plan. Shares vest and become exercisable in five equal annual installments of 72,000 shares beginning July 23, 2004.</footnote>
    <footnote id="F5">The price of the derivative security will be determined at a future date.</footnote>
  </footnotes>
  <ownerSignature>
    <signatureName>/s/ Eugene G. McCabe</signatureName>
    <signatureDate>2003-07-25</signatureDate>
  </ownerSignature>
</ownershipDocument>

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