-----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,
 NiOIhKw64261kx0JU1S1zYzHtSsCsRn7zmRcjCLl1SwSaOnPbQDiYotDYxuIZHNz
 0hjJFZZbF/WEbADLiwcigw==

<SEC-DOCUMENT>0000904454-10-000398.txt : 20101119
<SEC-HEADER>0000904454-10-000398.hdr.sgml : 20101119
<ACCEPTANCE-DATETIME>20101119190826
ACCESSION NUMBER:		0000904454-10-000398
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20101117
FILED AS OF DATE:		20101119
DATE AS OF CHANGE:		20101119

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Brown Stephanie L
		CENTRAL INDEX KEY:			0001405364

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34963
		FILM NUMBER:		101206934

	MAIL ADDRESS:	
		STREET 1:		C/O ONE BEACON STREET
		STREET 2:		22ND FLOOR
		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>2010-11-17</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001405364</rptOwnerCik>
            <rptOwnerName>Brown Stephanie L</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>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>MD &amp; General Counsel</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-11-17</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>125831</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>30.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>713041.8</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The Reporting Person holds such shares in the Stephanie L. Brown Trust.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Stephanie L. Brown</signatureName>
        <signatureDate>2010-11-19</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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