-----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,
 PV0+SspDgfTypjwwKUlsIKpBlOSgWLtPEA/5YjNBhjdxqnp/W+t3e/sqO4PbZwa5
 +XrOA5unpNhLZGDbbi1WDg==

<SEC-DOCUMENT>0001179110-03-003326.txt : 20030710
<SEC-HEADER>0001179110-03-003326.hdr.sgml : 20030710
<ACCEPTANCE-DATETIME>20030709182244
ACCESSION NUMBER:		0001179110-03-003326
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030709
FILED AS OF DATE:		20030710

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ADAPTEC INC
		CENTRAL INDEX KEY:			0000709804
		STANDARD INDUSTRIAL CLASSIFICATION:	COMPUTER COMMUNICATIONS EQUIPMENT [3576]
		IRS NUMBER:				942748530
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0331

	BUSINESS ADDRESS:	
		STREET 1:		691 S MILPITAS BLVD
		STREET 2:		M/S25
		CITY:			MILPITAS
		STATE:			CA
		ZIP:			95035
		BUSINESS PHONE:		4089458600

	MAIL ADDRESS:	
		STREET 1:		691 SOUTH MILPITAS BLVD
		STREET 2:		M/S25
		CITY:			MILPITAS
		STATE:			CA
		ZIP:			95035

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MOHR MARSHALL
		CENTRAL INDEX KEY:			0001252986

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-15071
		FILM NUMBER:		03780847

	BUSINESS ADDRESS:	
		STREET 1:		691 S. MILPITAS BLVD
		STREET 2:		C/O ADAPTEC INC
		CITY:			MILPITAS
		STATE:			CA
		ZIP:			95035
		BUSINESS PHONE:		4089458600

	MAIL ADDRESS:	
		STREET 1:		C/O ADAPTEC INC
		STREET 2:		691 S. MILPITAS BLVD
		CITY:			MILPITAS
		STATE:			CA
		ZIP:			95035
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType>
<periodOfReport>2003-07-09</periodOfReport>
<notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0000709804</issuerCik>
        <issuerName>ADAPTEC INC</issuerName>
        <issuerTradingSymbol>adpt</issuerTradingSymbol>
</issuer>
<reportingOwner><reportingOwnerId>
            <rptOwnerCik>0001252986</rptOwnerCik>
            <rptOwnerName>MOHR MARSHALL</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 and CFO</officerTitle>
<otherText></otherText>
</reportingOwnerRelationship>
</reportingOwner>
<derivativeSecurity><securityTitle><value>Incentive Stock Option</value>
</securityTitle>
<conversionOrExercisePrice><value>7.60</value>
</conversionOrExercisePrice>
<transactionDate><value>2003-07-07</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>A</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>65785</value>
</transactionShares>
<transactionValue><value>0</value>
</transactionValue>
<transactionAcquiredDisposedCode><value>A</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<exerciseDate><value>2008-07-07</value>
<footnoteId id="F1"></footnoteId>
</exerciseDate>
<expirationDate><value>2010-07-07</value>
</expirationDate>
<underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value>
</underlyingSecurityTitle>
<underlyingSecurityShares><value>65785</value>
</underlyingSecurityShares>
</underlyingSecurity>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>65785</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</derivativeSecurity>
<derivativeSecurity><securityTitle><value>Non Qualified Stock Option</value>
</securityTitle>
<conversionOrExercisePrice><value>7.60</value>
</conversionOrExercisePrice>
<transactionDate><value>2003-07-07</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>A</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>194215</value>
</transactionShares>
<transactionValue><value>0</value>
</transactionValue>
<transactionAcquiredDisposedCode><value>A</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<exerciseDate><value>2008-07-07</value>
<footnoteId id="F1"></footnoteId>
</exerciseDate>
<expirationDate><value>2010-07-07</value>
</expirationDate>
<underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value>
</underlyingSecurityTitle>
<underlyingSecurityShares><value>194215</value>
</underlyingSecurityShares>
</underlyingSecurity>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>194215</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</derivativeSecurity>
<footnotes><footnote id="F1">Mr. Mohr was granted a total of 260,000 options on July 7, 2003, of which 65,785 have been designated Incentive Stock Options and 194,215 which have been designated Non Qualified Stock Options. The aggregate of these options vest 20% on the first anniversary of the date of grant, and the balance vest in equal quarterly installments over 48 months thereafter.</footnote>
</footnotes>
<ownerSignature><signatureName>Marshall Mohr</signatureName>
<signatureDate>2003-07-09</signatureDate>
</ownerSignature>
</ownershipDocument>

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