TCLP TC Pipelines, LP - Common Units Representing Limited Partnership Interests (MM)

TC PipeLines, LP (NASDAQ: TCLP) (the Partnership) today announced that it has priced its debut public debt offering of $350 million of 4.65% Senior Notes due June 15, 2021 at a price of 99.83% of their face value. The offering of the Senior Notes is expected to settle on June 17, 2011, subject to customary closing conditions.

The Partnership also announced that the Senior Notes received investment grade credit ratings from the following agencies:

Standard & Poor's   BBB/Stable
Moody's             Baa2/Stable

The Partnership intends to use the net proceeds from the offering to repay the $61 million borrowed under its bridge loan facility and a repayment on its revolving credit facility associated with the recent acquisition of a 25 percent interest in each of Gas Transmission Northwest LLC (GTN) and Bison Pipeline LLC (Bison). The balance of the net proceeds will be used to repay $175 million of the Partnership's $475 million outstanding term loan under its credit facility.

J.P. Morgan and SunTrust Robinson Humphrey are acting as joint-bookrunning managers, Deutsche Bank Securities, HSBC and RBS are acting as senior co-managers and Mitsubishi UFJ Securities and Mizuho Securities are acting as junior co-managers for the offering. The offering is being made only by means of a prospectus supplement. A copy of the prospectus supplement and prospectus relating to the offering may be obtained from any of the following addresses:

J.P. Morgan                            SunTrust Robinson Humphrey
383 Madison Avenue                     3333 Peachtree Road, 11th Floor
New York, NY 10179                     Atlanta, GA 30326
Attn: High Grade Syndicate Desk -3rd   Mail Code: GA-ATLANTA-3947
 floor
Telephone: 212-834-4533                Attn: High Grade Debt Capital Markets
                                       Telephone: 1-800-685-4786

An electronic copy of the prospectus supplement and the prospectus are available from the Securities and Exchange Commission's (SEC) website at www.sec.gov. The notes are being offered pursuant to an effective shelf registration statement the Partnership previously filed with the SEC, which became automatically effective, by means of a prospectus and related prospectus supplement.

This news release does not constitute an offer to sell or a solicitation of an offer to buy the securities described herein, nor shall there be any sale of these securities in any state or jurisdiction in which such an offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. The offering may be made only by means of a prospectus and related prospectus supplement.

TC PipeLines, LP has interests in 5,560 miles of federally regulated U.S. interstate natural gas pipelines which serve markets across the United States and Eastern Canada. This includes significant interests in Great Lakes Gas Transmission Limited Partnership and Northern Border Pipeline Company as well as 25 percent ownership interest in each of Gas Transmission Northwest LLC, and Bison Pipeline LLC. TC PipeLines, LP also has 100 percent ownership of North Baja Pipeline, LLC and Tuscarora Gas Transmission Company. TC PipeLines, LP is managed by its general partner, TC PipeLines GP, Inc., an indirect wholly owned subsidiary of TransCanada Corporation. TC PipeLines GP, Inc. also holds common units of TC PipeLines, LP. Common units of TC PipeLines, LP are quoted on the NASDAQ Global Select Market and trade under the symbol "TCLP." For more information about TC PipeLines, LP, visit the Partnership's website at www.tcpipelineslp.com.

Cautionary Statement Regarding Forward-Looking Information

This news release may include "forward-looking statements" regarding future events and the future financial performance of TC PipeLines, LP. All statements other than statements of historical fact included or incorporated herein may constitute forward-looking statements. Words such as "anticipate," "believe," "continue," "estimate," "expect," "intend," "forecast," "project," "may," "plan," "strategy," and similar expressions identify forward-looking statements. All forward-looking statements are based on the Partnership's current beliefs as well as assumptions made by and information currently available to the Partnership. These statements reflect the Partnership's current views with respect to future events and are not guarantees of performance. Actual results may differ materially from those expressed or implied in these forward-looking statements and are subject to a number of risks and uncertainties. Important factors that could cause actual results to materially differ from the Partnership's current expectations include the demand for Great Lakes, Northern Border and GTN transportation in the future; the risk of a prolonged slowdown in growth or decline in the U.S. economy or the risk of delay in growth recovery in the U.S. economy; regulatory decisions, particularly those of the FERC; the ability of Great Lakes, Northern Border and GTN to recontract their available capacity on competitive terms; the Partnership's ability to identify and/or consummate accretive growth opportunities from TransCanada Corporation or others; the ability to access capital and credit markets with competitive rates and terms; operational decisions of the operator of our pipeline systems; the failure of a shipper on any one of the Partnership's pipelines to perform its contractual obligations; supply of natural gas in the Western Canada Sedimentary Basin and in competing basins, such as the Rocky Mountains; future demand for natural gas; overcapacity in the industry; success of other pipelines competing with Northern Border, Great Lakes and GTN by bringing competing U.S.-sourced gas to Northern Border's, Great Lakes' and GTN's markets; and other risks inherent in the transportation of natural gas as discussed in the Partnership's filings with the Securities and Exchange Commission (SEC), including its Annual Report on Form 10-K for the most recently completed fiscal year and its subsequently filed Quarterly Report on Form 10-Q. These filings are available to the public over the Internet at the SEC's website (www.sec.gov) and via the Partnership's website (www.tcpipelineslp.com). The Partnership disclaims any intention or obligation to update publicly or revise any such forward-looking statements, whether as a result of new information, future events or otherwise, occurring after the date hereof.

Contacts: TC PipeLines, LP Media Inquiries: Terry Cunha/Shawn Howard 403.920.7859 or 800.608.7859 TC PipeLines, LP Unitholder and Analyst Inquiries: Lee Evans 877.290.2772 investor_relations@tcpipelineslp.com www.tcpipelineslp.com