-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 SkiaSOIFm9savNlslvL/gU+iMe/2GE4jz1uv8r5OVubQ4uk2Ok9QXKryOQnAmUYQ
 Yt+AXC3WbfxwuCIiVMz1Jg==

<SEC-DOCUMENT>0000940394-08-000022.txt : 20080104
<SEC-HEADER>0000940394-08-000022.hdr.sgml : 20080104
<ACCEPTANCE-DATETIME>20080104135459
ACCESSION NUMBER:		0000940394-08-000022
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080101
FILED AS OF DATE:		20080104
DATE AS OF CHANGE:		20080104

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			EATON VANCE INSTITUTIONAL SENIOR FLOATING RATE FUND
		CENTRAL INDEX KEY:			0001080310
		IRS NUMBER:				043457431
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		THE EATON VANCE BUILDING
		STREET 2:		255 STATE STREET
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02109
		BUSINESS PHONE:		617-598-8880

	MAIL ADDRESS:	
		STREET 1:		THE EATON VANCE BUILDING
		STREET 2:		255 STATE STREET
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02109

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Maalouly Danny A
		CENTRAL INDEX KEY:			0001352649

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	811-09249
		FILM NUMBER:		08510662

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		617-482-8260

	MAIL ADDRESS:	
		STREET 1:		255 STATE STREET
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02109
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>maa37.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-01-01</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001080310</issuerCik>
        <issuerName>EATON VANCE INSTITUTIONAL SENIOR FLOATING RATE FUND</issuerName>
        <issuerTradingSymbol>EIFRX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001352649</rptOwnerCik>
            <rptOwnerName>Maalouly Danny A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>THE EATON VANCE BUILDING</rptOwnerStreet1>
            <rptOwnerStreet2>255 STATE STREET</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02109</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Treasurer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <footnotes></footnotes>

    <ownerSignature>
        <signatureName>By: Paul M. O'Neil / Attorney in Fact</signatureName>
        <signatureDate>2008-01-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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