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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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<SEC-DOCUMENT>0001104659-03-028414.txt : 20031212
<SEC-HEADER>0001104659-03-028414.hdr.sgml : 20031212
<ACCEPTANCE-DATETIME>20031212145702
ACCESSION NUMBER:		0001104659-03-028414
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20031211
FILED AS OF DATE:		20031212

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

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			FORMELA JEAN FRANCOIS
		CENTRAL INDEX KEY:			0001030575
		STATE OF INCORPORATION:			MA
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-30469
		FILM NUMBER:		031051657

	BUSINESS ADDRESS:	
		STREET 1:		C/O ATLAS VENTURE
		STREET 2:		890 WINTER STREET
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02451
		BUSINESS PHONE:		6178599290

	MAIL ADDRESS:	
		STREET 1:		C/O ATLAS VENTURE
		STREET 2:		890 WINTER STREET
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02451
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>a4.xml
<DESCRIPTION>4
<TEXT>
<XML>
<?xml version="1.0" encoding="utf-8"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>
  <periodOfReport>2003-12-11</periodOfReport>
  <notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0001022974</issuerCik>
        <issuerName>DECODE GENETICS INC</issuerName>
        <issuerTradingSymbol>DCGN</issuerTradingSymbol>
  </issuer>
  <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001030575</rptOwnerCik>
            <rptOwnerName>FORMELA JEAN FRANCOIS</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ATLAS VENTURE</rptOwnerStreet1>
            <rptOwnerStreet2>890 WINTER STREET, STE 320</rptOwnerStreet2>
            <rptOwnerCity>WALTHAM</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02451</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
      <isDirector>1</isDirector>
      <isOfficer>0</isOfficer>
      <isTenPercentOwner>0</isTenPercentOwner>
      <isOther>0</isOther>
    </reportingOwnerRelationship>
  </reportingOwner>
  <nonDerivativeTable>
    <nonDerivativeTransaction>
      <securityTitle>
        <value>Common Stock</value>
      </securityTitle>
      <transactionDate>
        <value>2003-12-11</value>
      </transactionDate>
      <transactionCoding>
        <transactionFormType>4</transactionFormType>
        <transactionCode>S</transactionCode>
        <equitySwapInvolved>0</equitySwapInvolved>
      </transactionCoding>
      <transactionTimeliness>
        <value></value>
      </transactionTimeliness>
      <transactionAmounts>
        <transactionShares>
          <value>9805</value>
        </transactionShares>
        <transactionPricePerShare>
          <value>8.1372</value>
        </transactionPricePerShare>
        <transactionAcquiredDisposedCode>
          <value>D</value>
        </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
          <value>0</value>
        </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
        <directOrIndirectOwnership>
          <value>I</value>
        </directOrIndirectOwnership>
        <natureOfOwnership>
          <value>See</value>
          <footnoteId id="F1"/>
        </natureOfOwnership>
      </ownershipNature>
    </nonDerivativeTransaction>
    <nonDerivativeTransaction>
      <securityTitle>
        <value>Common Stock</value>
      </securityTitle>
      <transactionDate>
        <value>2003-12-11</value>
      </transactionDate>
      <transactionCoding>
        <transactionFormType>4</transactionFormType>
        <transactionCode>S</transactionCode>
        <equitySwapInvolved>0</equitySwapInvolved>
      </transactionCoding>
      <transactionTimeliness>
        <value></value>
      </transactionTimeliness>
      <transactionAmounts>
        <transactionShares>
          <value>9805</value>
        </transactionShares>
        <transactionPricePerShare>
          <value>8.1372</value>
        </transactionPricePerShare>
        <transactionAcquiredDisposedCode>
          <value>D</value>
        </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
          <value>0</value>
        </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
        <directOrIndirectOwnership>
          <value>I</value>
        </directOrIndirectOwnership>
        <natureOfOwnership>
          <value>See</value>
          <footnoteId id="F2"/>
        </natureOfOwnership>
      </ownershipNature>
    </nonDerivativeTransaction>
  </nonDerivativeTable>
  <footnotes>
    <footnote id="F1">The reported securities were held by Atlas Venture Fund II, L.P.  The reporting person is a general partner of Atlas Venture Associates II, L.P., which is the sole general partner of Atlas Venture Fund II, L.P.  The reporting person disclaims beneficial ownership of the reported securities except to the extent of his pecuniary interest therein.</footnote>
    <footnote id="F2">The reported securities were held by Atlas Venture Europe Fund B.V.   The reporting person is a general partner of Atlas Venture Associates II, L.P., which is the sole general partner of Atlas Venture Fund II, L.P.  Atlas Venture Europe Fund B.V. is a majority owned subsidiary of Atlas InvesteringsGroep N.V, which is a limited partner in Atlas Venture Fund II, L.P.  The reporting person disclaims beneficial ownership of the reported securities except to the extent of his pecuniary interest therein.</footnote>
  </footnotes>
  <ownerSignature>
    <signatureName>/s/ Jeanne Larkin Henry, as Attorney in Fact</signatureName>
    <signatureDate>2003-12-12</signatureDate>
  </ownerSignature>
</ownershipDocument>

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