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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>0000904454-10-000493.txt : 20101203
<SEC-HEADER>0000904454-10-000493.hdr.sgml : 20101203
<ACCEPTANCE-DATETIME>20101203181145
ACCESSION NUMBER:		0000904454-10-000493
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20101201
FILED AS OF DATE:		20101203
DATE AS OF CHANGE:		20101203

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Brennan John Joseph
		CENTRAL INDEX KEY:			0001485472

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34963
		FILM NUMBER:		101232629

	MAIL ADDRESS:	
		STREET 1:		ONE BEACON STREET
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02108

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			LPL Investment Holdings Inc.
		CENTRAL INDEX KEY:			0001397911
		STANDARD INDUSTRIAL CLASSIFICATION:	SECURITY & COMMODITY BROKERS, DEALERS, EXCHANGES & SERVICES [6200]
		IRS NUMBER:				203717839
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		ONE BEACON STREET , FLOOR 22
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02108
		BUSINESS PHONE:		617 423 3644

	MAIL ADDRESS:	
		STREET 1:		ONE BEACON STREET , FLOOR 22
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02108
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-12-01</periodOfReport>

    <issuer>
        <issuerCik>0001397911</issuerCik>
        <issuerName>LPL Investment Holdings Inc.</issuerName>
        <issuerTradingSymbol>LPLA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001485472</rptOwnerCik>
            <rptOwnerName>Brennan John Joseph</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O LPL INVESTMENT HOLDINGS INC.</rptOwnerStreet1>
            <rptOwnerStreet2>ONE BEACON STREET</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02108</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2010-12-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1428</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>23564</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These shares represent restricted stock that was granted under the Issuer's 2010 Omnibus Equity Incentive Plan.  This restricted stock shall be fully vested on the second anniversary of the transaction date.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Chad D. Perry, as Attorney-in-Fact</signatureName>
        <signatureDate>2010-12-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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