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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,
 T+e4WpRVCnTkYIexW8mafvgZPoclQizZkttPBlRPo2D/hTurQSn2NwinuoAmL7ZR
 dZLmlVqiZkltHkFRGuQJ6A==

<SEC-DOCUMENT>0001140361-10-009906.txt : 20100304
<SEC-HEADER>0001140361-10-009906.hdr.sgml : 20100304
<ACCEPTANCE-DATETIME>20100304112043
ACCESSION NUMBER:		0001140361-10-009906
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100301
FILED AS OF DATE:		20100304
DATE AS OF CHANGE:		20100304

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Baggs James M
		CENTRAL INDEX KEY:			0001485454

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-26091
		FILM NUMBER:		10655951

	MAIL ADDRESS:	
		STREET 1:		450 - 1 STREET SW
		CITY:			CALGARY
		STATE:			A0
		ZIP:			T2P 5H1

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			TC PIPELINES LP
		CENTRAL INDEX KEY:			0001075607
		STANDARD INDUSTRIAL CLASSIFICATION:	NATURAL GAS TRANSMISSION [4922]
		IRS NUMBER:				522135448
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		717 TEXAS STREET, SUITE #2400
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77002
		BUSINESS PHONE:		(877) 290-2772

	MAIL ADDRESS:	
		STREET 1:		717 TEXAS STREET, SUITE #2400
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77002
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 3
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0203</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2010-03-01</periodOfReport>

    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001075607</issuerCik>
        <issuerName>TC PIPELINES LP</issuerName>
        <issuerTradingSymbol>TCLP</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001485454</rptOwnerCik>
            <rptOwnerName>Baggs James M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>450 - 1 STREET SW</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CALGARY</rptOwnerCity>
            <rptOwnerState>A0</rptOwnerState>
            <rptOwnerZipCode>T2P 5H1</rptOwnerZipCode>
            <rptOwnerStateDescription>ALBERTA, CANADA</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes></footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Donald J. DeGrandis, Attorney for James M. Baggs</signatureName>
        <signatureDate>2010-03-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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