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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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 9VXkz77xvh3VJU3CcZ/tKg==

<SEC-DOCUMENT>0001073880-09-000003.txt : 20091211
<SEC-HEADER>0001073880-09-000003.hdr.sgml : 20091211
<ACCEPTANCE-DATETIME>20091210184652
ACCESSION NUMBER:		0001073880-09-000003
CONFORMED SUBMISSION TYPE:	D/A
PUBLIC DOCUMENT COUNT:		1
ITEM INFORMATION:		Rule 506
ITEM INFORMATION:		Investment Company Act Section 3(c)
ITEM INFORMATION:		Section 3(c)(1)
FILED AS OF DATE:		20091211
DATE AS OF CHANGE:		20091210
EFFECTIVENESS DATE:		20091211

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			JANUS INSTITUTIONAL CONCENTRATED GROWTH PORTFOLIO
		CENTRAL INDEX KEY:			0001073880
		IRS NUMBER:				046876976
		STATE OF INCORPORATION:			NH
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		D/A
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	021-44576
		FILM NUMBER:		091234797

	BUSINESS ADDRESS:	
		STREET 1:		151 DETROIT ST.
		CITY:			DENVER
		STATE:			CO
		ZIP:			80206
		BUSINESS PHONE:		303-333-3863

	MAIL ADDRESS:	
		STREET 1:		151 DETROIT ST.
		CITY:			DENVER
		STATE:			CO
		ZIP:			80206

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	JANUS INSTITUTIONAL AGGRESSIVE GROWTH PORTFOLIO
		DATE OF NAME CHANGE:	19981117
</SEC-HEADER>
<DOCUMENT>
<TYPE>D/A
<SEQUENCE>1
<FILENAME>primary_doc.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<edgarSubmission>

    <schemaVersion>X0603</schemaVersion>

    <submissionType>D/A</submissionType>

    <testOrLive>LIVE</testOrLive>

    <primaryIssuer>
        <cik>0001073880</cik>
        <entityName>JANUS INSTITUTIONAL CONCENTRATED GROWTH PORTFOLIO</entityName>
        <issuerAddress>
            <street1>151 DETROIT ST.</street1>
            <city>DENVER</city>
            <stateOrCountry>CO</stateOrCountry>
            <zipCode>80206</zipCode>
        </issuerAddress>
        <issuerPhoneNumber>303-333-3863</issuerPhoneNumber>
        <jurisdictionOfInc>NEW HAMPSHIRE</jurisdictionOfInc>
        <edgarPreviousNameList>
            <previousName>JANUS INSTITUTIONAL AGGRESSIVE GROWTH PORTFOLIO</previousName>
        </edgarPreviousNameList>
        <entityType>Business Trust</entityType>
        <yearOfInc>
            <overFiveYears>true</overFiveYears>
        </yearOfInc>
    </primaryIssuer>

    <relatedPersonsList>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Dan</firstName>
                <lastName>Charles</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>151 Detroit St.</street1>
                <city>Denver</city>
                <stateOrCountry>CO</stateOrCountry>
                <zipCode>80206</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Gregory</firstName>
                <middleName>A.</middleName>
                <lastName>Frost</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>151 Detroit St.</street1>
                <city>Denver</city>
                <stateOrCountry>CO</stateOrCountry>
                <zipCode>80206</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Heidi</firstName>
                <lastName>Hardin</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>151 Detroit St.</street1>
                <city>Denver</city>
                <stateOrCountry>CO</stateOrCountry>
                <zipCode>80206</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Nancy</firstName>
                <lastName>Holden</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>151 Detroit St.</street1>
                <city>Denver</city>
                <stateOrCountry>CO</stateOrCountry>
                <zipCode>80206</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Frank</firstName>
                <lastName>Lao</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>151 Detroit St.</street1>
                <city>Denver</city>
                <stateOrCountry>CO</stateOrCountry>
                <zipCode>80206</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Jesper</firstName>
                <lastName>Nergaard</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>151 Detroit St.</street1>
                <city>Denver</city>
                <stateOrCountry>CO</stateOrCountry>
                <zipCode>80206</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Carolyn</firstName>
                <middleName>Patton</middleName>
                <lastName>Piskun</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>151 Detroit St.</street1>
                <city>Denver</city>
                <stateOrCountry>CO</stateOrCountry>
                <zipCode>80206</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Michelle</firstName>
                <lastName>Rosenberg</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>151 Detroit St.</street1>
                <city>Denver</city>
                <stateOrCountry>CO</stateOrCountry>
                <zipCode>80206</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
    </relatedPersonsList>

    <offeringData>
        <industryGroup>
            <industryGroupType>Pooled Investment Fund</industryGroupType>
            <investmentFundInfo>
                <investmentFundType>Private Equity Fund</investmentFundType>
                <is40Act>false</is40Act>
            </investmentFundInfo>
        </industryGroup>
        <issuerSize>
            <revenueRange>Decline to Disclose</revenueRange>
        </issuerSize>
        <federalExemptionsExclusions>
            <item>06</item>
            <item>3C</item>
            <item>3C.1</item>
        </federalExemptionsExclusions>
        <typeOfFiling>
            <newOrAmendment>
                <isAmendment>true</isAmendment>
                <previousAccessionNumber>9999999997-08-032225</previousAccessionNumber>
            </newOrAmendment>
            <dateOfFirstSale>
                <value>1998-11-02</value>
            </dateOfFirstSale>
        </typeOfFiling>
        <durationOfOffering>
            <moreThanOneYear>true</moreThanOneYear>
        </durationOfOffering>
        <typesOfSecuritiesOffered>
            <isPooledInvestmentFundType>true</isPooledInvestmentFundType>
        </typesOfSecuritiesOffered>
        <businessCombinationTransaction>
            <isBusinessCombinationTransaction>false</isBusinessCombinationTransaction>
            <clarificationOfResponse></clarificationOfResponse>
        </businessCombinationTransaction>
        <minimumInvestmentAccepted>5000000</minimumInvestmentAccepted>
        <salesCompensationList></salesCompensationList>
        <offeringSalesAmounts>
            <totalOfferingAmount>Indefinite</totalOfferingAmount>
            <totalAmountSold>53941742</totalAmountSold>
            <totalRemaining>Indefinite</totalRemaining>
            <clarificationOfResponse></clarificationOfResponse>
        </offeringSalesAmounts>
        <investors>
            <hasNonAccreditedInvestors>false</hasNonAccreditedInvestors>
            <totalNumberAlreadyInvested>12</totalNumberAlreadyInvested>
        </investors>
        <salesCommissionsFindersFees>
            <salesCommissions>
                <dollarAmount>0</dollarAmount>
            </salesCommissions>
            <findersFees>
                <dollarAmount>0</dollarAmount>
            </findersFees>
            <clarificationOfResponse></clarificationOfResponse>
        </salesCommissionsFindersFees>
        <useOfProceeds>
            <grossProceedsUsed>
                <dollarAmount>0</dollarAmount>
            </grossProceedsUsed>
            <clarificationOfResponse></clarificationOfResponse>
        </useOfProceeds>
        <signatureBlock>
            <authorizedRepresentative>false</authorizedRepresentative>
            <signature>
                <issuerName>JANUS INSTITUTIONAL CONCENTRATED GROWTH PORTFOLIO</issuerName>
                <signatureName>Michelle Rosenberg</signatureName>
                <nameOfSigner>Michelle Rosenberg</nameOfSigner>
                <signatureTitle>Vice President</signatureTitle>
                <signatureDate>2009-12-10</signatureDate>
            </signature>
        </signatureBlock>
    </offeringData>
</edgarSubmission>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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