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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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<SEC-DOCUMENT>0001479191-09-000001.txt : 20091229
<SEC-HEADER>0001479191-09-000001.hdr.sgml : 20091229
<ACCEPTANCE-DATETIME>20091229132936
ACCESSION NUMBER:		0001479191-09-000001
CONFORMED SUBMISSION TYPE:	D
PUBLIC DOCUMENT COUNT:		1
ITEM INFORMATION:		Rule 506
ITEM INFORMATION:		Investment Company Act Section 3(c)
ITEM INFORMATION:		Section 3(c)(7)
FILED AS OF DATE:		20091229
DATE AS OF CHANGE:		20091229
EFFECTIVENESS DATE:		20091229

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Institutional Cash Series plc
		CENTRAL INDEX KEY:			0001479191
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			L2
		FISCAL YEAR END:			0930

	FILING VALUES:
		FORM TYPE:		D
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	021-137244
		FILM NUMBER:		091263463

	BUSINESS ADDRESS:	
		STREET 1:		GUILD HOUSE, GUILD STREET
		STREET 2:		INTERNATIONAL FINANCIAL SERVICES CENTRE
		CITY:			DUBLIN 1
		STATE:			L2
		ZIP:			00000
		BUSINESS PHONE:		353 1 853 3000

	MAIL ADDRESS:	
		STREET 1:		GUILD HOUSE, GUILD STREET
		STREET 2:		INTERNATIONAL FINANCIAL SERVICES CENTRE
		CITY:			DUBLIN 1
		STATE:			L2
		ZIP:			00000
</SEC-HEADER>
<DOCUMENT>
<TYPE>D
<SEQUENCE>1
<FILENAME>primary_doc.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<edgarSubmission>

    <schemaVersion>X0603</schemaVersion>

    <submissionType>D</submissionType>

    <testOrLive>LIVE</testOrLive>

    <primaryIssuer>
        <cik>0001479191</cik>
        <entityName>Institutional Cash Series plc</entityName>
        <issuerAddress>
            <street1>GUILD HOUSE, GUILD STREET</street1>
            <street2>INTERNATIONAL FINANCIAL SERVICES CENTRE</street2>
            <city>DUBLIN 1</city>
            <stateOrCountry>L2</stateOrCountry>
            <zipCode>00000</zipCode>
        </issuerAddress>
        <issuerPhoneNumber>353 1 853 3000</issuerPhoneNumber>
        <jurisdictionOfInc>IRELAND</jurisdictionOfInc>
        <issuerPreviousNameList>
            <previousName>Merrill Lynch Institutional Liquidity Funds plc</previousName>
            <previousName>Merrill Lynch Mercury Institutional Liquidity Funds plc</previousName>
        </issuerPreviousNameList>
        <edgarPreviousNameList>
            <value>None</value>
        </edgarPreviousNameList>
        <entityType>Other</entityType>
        <entityTypeOtherDesc>Public Limited Company</entityTypeOtherDesc>
        <yearOfInc>
            <overFiveYears>true</overFiveYears>
        </yearOfInc>
    </primaryIssuer>

    <relatedPersonsList>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>n/a</firstName>
                <lastName>BlackRock Investment Management (Dublin) Limited</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>Fitzwilton House, Wilton Place</street1>
                <city>Dublin</city>
                <stateOrCountry>L2</stateOrCountry>
                <zipCode>2</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Executive Officer</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification>Manager</relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Nicholas</firstName>
                <middleName>C.D.</middleName>
                <lastName>Hall</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>BlackRock Investment Management (UK) Ltd</street1>
                <street2>33 King William Street</street2>
                <city>London</city>
                <stateOrCountry>X0</stateOrCountry>
                <zipCode>EC4R 9AS</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Daniel</firstName>
                <lastName>Morrissey</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>BlackRock Investment Management (Dublin)</street1>
                <street2>Fitzwilton House, Wilton Place</street2>
                <city>Dublin</city>
                <stateOrCountry>L2</stateOrCountry>
                <zipCode>2</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Desmond</firstName>
                <lastName>Murray</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>BlackRock Investment Management (Dublin)</street1>
                <street2>Fitzwilton House, Wilton Place</street2>
                <city>Dublin</city>
                <stateOrCountry>L2</stateOrCountry>
                <zipCode>2</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Jane</firstName>
                <lastName>Richardson</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>BlackRock Investment Management (Dublin)</street1>
                <street2>Fitzwilton House, Wilton Place</street2>
                <city>Dublin</city>
                <stateOrCountry>L2</stateOrCountry>
                <zipCode>2</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
        <relatedPersonInfo>
            <relatedPersonName>
                <firstName>Ronald</firstName>
                <middleName>C</middleName>
                <lastName>Spencer</lastName>
            </relatedPersonName>
            <relatedPersonAddress>
                <street1>BlackRock Investment Management (Dublin)</street1>
                <street2>Fitzwilton House, Wilton Place</street2>
                <city>Dublin</city>
                <stateOrCountry>L2</stateOrCountry>
                <zipCode>2</zipCode>
            </relatedPersonAddress>
            <relatedPersonRelationshipList>
                <relationship>Director</relationship>
            </relatedPersonRelationshipList>
            <relationshipClarification></relationshipClarification>
        </relatedPersonInfo>
    </relatedPersonsList>

    <offeringData>
        <industryGroup>
            <industryGroupType>Pooled Investment Fund</industryGroupType>
            <investmentFundInfo>
                <investmentFundType>Other Investment Fund</investmentFundType>
                <is40Act>false</is40Act>
            </investmentFundInfo>
        </industryGroup>
        <issuerSize>
            <aggregateNetAssetValueRange>Decline to Disclose</aggregateNetAssetValueRange>
        </issuerSize>
        <federalExemptionsExclusions>
            <item>06</item>
            <item>3C</item>
            <item>3C.7</item>
        </federalExemptionsExclusions>
        <typeOfFiling>
            <newOrAmendment>
                <isAmendment>false</isAmendment>
            </newOrAmendment>
            <dateOfFirstSale>
                <value>2005-03-29</value>
            </dateOfFirstSale>
        </typeOfFiling>
        <durationOfOffering>
            <moreThanOneYear>true</moreThanOneYear>
        </durationOfOffering>
        <typesOfSecuritiesOffered>
            <isPooledInvestmentFundType>true</isPooledInvestmentFundType>
        </typesOfSecuritiesOffered>
        <businessCombinationTransaction>
            <isBusinessCombinationTransaction>false</isBusinessCombinationTransaction>
            <clarificationOfResponse></clarificationOfResponse>
        </businessCombinationTransaction>
        <minimumInvestmentAccepted>250000</minimumInvestmentAccepted>
        <salesCompensationList></salesCompensationList>
        <offeringSalesAmounts>
            <totalOfferingAmount>Indefinite</totalOfferingAmount>
            <totalAmountSold>3502772319</totalAmountSold>
            <totalRemaining>Indefinite</totalRemaining>
            <clarificationOfResponse></clarificationOfResponse>
        </offeringSalesAmounts>
        <investors>
            <hasNonAccreditedInvestors>false</hasNonAccreditedInvestors>
            <totalNumberAlreadyInvested>35</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>Institutional Cash Series plc</issuerName>
                <signatureName>Desmond Murray</signatureName>
                <nameOfSigner>Desmond Murray</nameOfSigner>
                <signatureTitle>Director</signatureTitle>
                <signatureDate>2009-12-29</signatureDate>
            </signature>
        </signatureBlock>
    </offeringData>
</edgarSubmission>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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