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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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 TKSxcF10Kqyn+sffugcJMg==

<SEC-DOCUMENT>0000874294-04-000024.txt : 20040129
<SEC-HEADER>0000874294-04-000024.hdr.sgml : 20040129
<ACCEPTANCE-DATETIME>20040129181627
ACCESSION NUMBER:		0000874294-04-000024
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20040129
FILED AS OF DATE:		20040129

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ICOS CORP / DE
		CENTRAL INDEX KEY:			0000874294
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				911463450
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		22021-20TH AVENUE S.E.,
		CITY:			BOTHELL
		STATE:			WA
		ZIP:			98021
		BUSINESS PHONE:		2064851900

	MAIL ADDRESS:	
		STREET 1:		22021 20TH AVE SE
		CITY:			BOTHELL
		STATE:			WA
		ZIP:			98021

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SCHULER JACK W
		CENTRAL INDEX KEY:			0001021412

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-19171
		FILM NUMBER:		04553721

	BUSINESS ADDRESS:	
		STREET 1:		1910 INNOVATION WAY
		CITY:			TUCSON
		STATE:			AZ
		ZIP:			85737
		BUSINESS PHONE:		8479401700

	MAIL ADDRESS:	
		STREET 1:		1910 INNOVATION WAY
		CITY:			TUCSON
		STATE:			AZ
		ZIP:			85737
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>sch39.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-01-29</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000874294</issuerCik>
        <issuerName>ICOS CORP / DE</issuerName>
        <issuerTradingSymbol>ICOS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001021412</rptOwnerCik>
            <rptOwnerName>SCHULER JACK W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>22021 - 20TH AVENUE SE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BOTHELL</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98021</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>43.1600</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2004-01-29</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>30000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-01-29</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>30000.00</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>30000.00</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Vests in two equal amounts as of each of the next two annual stockholder's meetings of ICOS Corporation, assuming continued service on the Board of Directors of ICOS Corporation during such periods; provided, however, that in the event this grant is made within five months prior to an annual meeting of stockholders, vesting shall not commence until the second annual meeting after the date of grant.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>By: /s/ Susan Aznoff as Attorney-in-Fact</signatureName>
        <signatureDate>2004-01-29</signatureDate>
    </ownerSignature>
</ownershipDocument>

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