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                                                                     EXHIBIT 5.1

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June 19th, 2003                                  TransCanada PipeLines Tower
TransCanada Corporation                          450 -1st Street S.W.
450-1st Street S.W.                              Calgary, Alberta, Canada T2P 5H1
Calgary, Alberta, Canada                         tel 403.920.7770
T2P 5H1                                          fax 403.920.2410
                                                 email al_bellstedt@transcanada.com
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Ladies and Gentlemen:

    I am Executive Vice-President, Law and General Counsel of TransCanada
Corporation, a corporation organized under the laws of Canada (the
"Corporation"). This legal opinion is being rendered in connection with
Post-Effective Amendment No. 1 to the Registration Statement on Form F-3 (File
No. 333-6132) (the "Registration Statement"), to be filed with the Securities
and Exchange Commission (the "Commission") in connection with the registration
under the Securities Act of 1933, as amended (the "Securities Act"), of common
shares of the Corporation (the "Common Shares") to be issued pursuant to
TransCanada Corporation's Dividend Reinvestment and Share Purchase Plan (the
"Plan"). The Corporation is making such filing as successor issuer to
TransCanada PipeLines Limited, a corporation organized under the laws of Canada,
pursuant to Rule 414 under the Securities Act.

    I have examined originals or copies, certified or otherwise identified to my
satisfaction, of such public and corporate records, certificates, instruments
and other documents and have considered such questions of law as I have deemed
necessary or appropriate to enable me to render the opinion hereinafter
expressed. In such examination I have assumed the genuineness of all signatures,
the authenticity of all documents submitted to me as originals and the
conformity to original documents of all documents submitted to me as copies,
certified or otherwise.

    The opinion hereinafter expressed is limited to matters governed by the laws
of the Province of Alberta and the laws of Canada applicable therein.

    Based and relying upon the foregoing, I am of the opinion that the Common
Shares, when issued in accordance with the terms of the Plan, shall be validly
issued, fully paid and non-assessable.

    I hereby consent to the filing of this opinion as an exhibit to the
Registration Statement.

Yours truly,

/s/ Albrecht W. A. Bellstedt

ALBRECHT W. A. BELLSTEDT
EXECUTIVE VICE-PRESIDENT,
LAW AND GENERAL COUNSEL