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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 J98k9NilhlJySClVu8VPjZEYbVqqLY2Yr++HHZa3YnLbOHTYEkfWkp9JtYuRs8Cd
 tmNB7JKrpnfnMc00Yef5vQ==

<SEC-DOCUMENT>0000902664-07-001042.txt : 20070220
<SEC-HEADER>0000902664-07-001042.hdr.sgml : 20070219
<ACCEPTANCE-DATETIME>20070220170903
ACCESSION NUMBER:		0000902664-07-001042
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20070208
FILED AS OF DATE:		20070220
DATE AS OF CHANGE:		20070220

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			OLD MUTUAL 2100 ABSOLUTE RETURN INSTITUTIONAL FUND, LLC
		CENTRAL INDEX KEY:			0001384358
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		RIVERVIEW PLAZA
		STREET 2:		287 BOWMAN AVENUE, SECOND FLOOR
		CITY:			PURCHASE
		STATE:			NY
		ZIP:			10577
		BUSINESS PHONE:		914 251-1200

	MAIL ADDRESS:	
		STREET 1:		RIVERVIEW PLAZA
		STREET 2:		287 BOWMAN AVENUE, SECOND FLOOR
		CITY:			PURCHASE
		STATE:			NY
		ZIP:			10577

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			OLD MUTUAL (US) HOLDINGS INC.
		CENTRAL INDEX KEY:			0000796370
		STANDARD INDUSTRIAL CLASSIFICATION:	INVESTMENT ADVICE [6282]
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	811-21998
		FILM NUMBER:		07636282

	BUSINESS ADDRESS:	
		STREET 1:		200 CLARENDON STREET, 53RD FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116
		BUSINESS PHONE:		(617) 369-7300

	MAIL ADDRESS:	
		STREET 1:		200 CLARENDON STREET, 53RD FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116

	FORMER NAME:	
		FORMER CONFORMED NAME:	UNITED ASSET MANAGEMENT CORP
		DATE OF NAME CHANGE:	19920703
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>form3_ex.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2007-02-08</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001384358</issuerCik>
        <issuerName>OLD MUTUAL 2100 ABSOLUTE RETURN INSTITUTIONAL FUND, LLC</issuerName>
        <issuerTradingSymbol>NONE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000796370</rptOwnerCik>
            <rptOwnerName>OLD MUTUAL (US) HOLDINGS INC.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 CLARENDON STREET, 53RD FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>See Remarks</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Limited Liability Company Interests</value>
            </securityTitle>
            <postTransactionAmounts>
                <valueOwnedFollowingTransaction>
                    <value>100000</value>
                </valueOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <remarks>This filing is made on behalf of Old Mutual (US) Holdings, Inc., the parent of 2100 Larch Lane LLC, the Issuer's investment
 adviser.  The Investment Management Agreement of the Issuer is dated February 8, 2007.  The Reporting Person made a seed
 investment of $100,000 in the Issuer.</remarks>

    <ownerSignature>
        <signatureName>/s/ John M. Grady</signatureName>
        <signatureDate>2007-02-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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