-----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,
 GxgMH4wrEbfgkq4dE+qvnjtKoOZ60Wh2GfrPpaDQiBc/xzvZQdyGPBIoqAwq/3Y+
 Mtaj+DoPzlcX/FS9YiwMQw==

<SEC-DOCUMENT>0001104659-03-015759.txt : 20030728
<SEC-HEADER>0001104659-03-015759.hdr.sgml : 20030728
<ACCEPTANCE-DATETIME>20030725194106
ACCESSION NUMBER:		0001104659-03-015759
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:			YOUNGJOHNS ROBERT
		CENTRAL INDEX KEY:			0001220078

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-15086
		FILM NUMBER:		03804491

	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>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>0001220078</rptOwnerCik>
            <rptOwnerName>YOUNGJOHNS ROBERT</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>Executive Vice President</officerTitle>
    </reportingOwnerRelationship>
  </reportingOwner>
  <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>500000</value>
      </transactionShares>
      <transactionValue>
        <value>0</value>
        <footnoteId id="F2"/>
      </transactionValue>
      <transactionAcquiredDisposedCode>
        <value>A</value>
      </transactionAcquiredDisposedCode>
    </transactionAmounts>
    <exerciseDate>
      <value>2004-07-23</value>
      <footnoteId id="F1"/>
    </exerciseDate>
    <expirationDate>
      <value>2013-07-23</value>
    </expirationDate>
    <underlyingSecurity>
      <underlyingSecurityTitle>
        <value>Common Stock</value>
      </underlyingSecurityTitle>
      <underlyingSecurityShares>
        <value>500000</value>
      </underlyingSecurityShares>
    </underlyingSecurity>
    <postTransactionAmounts>
      <sharesOwnedFollowingTransaction>
        <value>500000</value>
      </sharesOwnedFollowingTransaction>
    </postTransactionAmounts>
    <ownershipNature>
      <directOrIndirectOwnership>
        <value>D</value>
      </directOrIndirectOwnership>
    </ownershipNature>
  </derivativeSecurity>
  <footnotes>
    <footnote id="F1">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 100,000 shares beginning July 23, 2004.</footnote>
    <footnote id="F2">The price of the derivative security will be determined at a future date.</footnote>
  </footnotes>
  <ownerSignature>
    <signatureName>/s/ Robert H. Youngjohns</signatureName>
    <signatureDate>2003-07-25</signatureDate>
  </ownerSignature>
</ownershipDocument>

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