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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 Daf9jlr30g2DjNIXvkJ87w==

<SEC-DOCUMENT>0001104659-08-059471.txt : 20080918
<SEC-HEADER>0001104659-08-059471.hdr.sgml : 20080918
<ACCEPTANCE-DATETIME>20080918180208
ACCESSION NUMBER:		0001104659-08-059471
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080916
FILED AS OF DATE:		20080918
DATE AS OF CHANGE:		20080918

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Sigurdsson Jakob O
		CENTRAL INDEX KEY:			0001378318

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-30469
		FILM NUMBER:		081079109

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		354-570-1900

	MAIL ADDRESS:	
		STREET 1:		C/O DECODE GENETICS, INC.
		STREET 2:		STURLUGATA 8
		CITY:			REYKJAVIK
		STATE:			K6
		ZIP:			IS-101

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			DECODE GENETICS INC
		CENTRAL INDEX KEY:			0001022974
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-COMMERCIAL PHYSICAL & BIOLOGICAL RESEARCH [8731]
		IRS NUMBER:				043326704
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		8 STURLUGATA
		STREET 2:		IS 101
		CITY:			REYJKAVIK
		STATE:			K6
		ZIP:			00000
		BUSINESS PHONE:		011 354 570 1900

	MAIL ADDRESS:	
		STREET 1:		8 STURLUGATA
		STREET 2:		IS 101
		CITY:			REYKJAVIK
		STATE:			K6
		ZIP:			00000
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>a4.xml
<DESCRIPTION>4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-09-16</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001022974</issuerCik>
        <issuerName>DECODE GENETICS INC</issuerName>
        <issuerTradingSymbol>DCGN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001378318</rptOwnerCik>
            <rptOwnerName>Sigurdsson Jakob O</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O DECODE GENETICS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>STURLUGATA 8</rptOwnerStreet2>
            <rptOwnerCity>REYKJAVIK</rptOwnerCity>
            <rptOwnerState>K6</rptOwnerState>
            <rptOwnerZipCode>IS-101</rptOwnerZipCode>
            <rptOwnerStateDescription>ICELAND</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>S.V.P., Corporate Development</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-09-16</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1871</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.6504</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>379</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>/s/ Jakob O. Sigurdsson</signatureName>
        <signatureDate>2008-09-18</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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