-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 VlhjGssgKRATuRTAfCQWSw==

<SEC-DOCUMENT>0001478268-10-000017.txt : 20100201
<SEC-HEADER>0001478268-10-000017.hdr.sgml : 20100201
<ACCEPTANCE-DATETIME>20100201170320
ACCESSION NUMBER:		0001478268-10-000017
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100201
FILED AS OF DATE:		20100201
DATE AS OF CHANGE:		20100201

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Endowment Institutional Fund, L.P.
		CENTRAL INDEX KEY:			0001478268
		IRS NUMBER:				271402213
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		4265 SAN FELIPE
		STREET 2:		8TH FLOOR
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77027
		BUSINESS PHONE:		713-993-4675

	MAIL ADDRESS:	
		STREET 1:		4265 SAN FELIPE
		STREET 2:		8TH FLOOR
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77027

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BLAISDELL JOHN A
		CENTRAL INDEX KEY:			0001282437

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	811-22367
		FILM NUMBER:		10564071

	MAIL ADDRESS:	
		STREET 1:		4265 SAN FELIPE STREET
		STREET 2:		8TH FLOOR
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77027
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-02-01</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001478268</issuerCik>
        <issuerName>Endowment Institutional Fund, L.P.</issuerName>
        <issuerTradingSymbol>None</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001282437</rptOwnerCik>
            <rptOwnerName>BLAISDELL JOHN A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>4265 SAN FELIPE STREET</rptOwnerStreet1>
            <rptOwnerStreet2>8TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77027</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Co-Principal Executive Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Limited Partnership Interests</value>
            </securityTitle>
            <transactionDate>
                <value>2010-02-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>100000</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <valueOwnedFollowingTransaction>
                    <value>1000000</value>
                </valueOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The securities are limited partnership interests. Holders are deemed to own a single interest, regardless of the amount of the interest.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>John A. Blaisdell</signatureName>
        <signatureDate>2010-02-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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