EXHIBIT 5.1


                      [LOCKE LIDDELL & SAPP LLP LETTERHEAD]


June 5, 2002


Board of Directors
Tennessee Gas Pipeline Company
El Paso Building
1001 Louisiana Street
Houston, Texas 77002

Gentlemen:

         We have acted as counsel to Tennessee Gas Pipeline Company, a Delaware
corporation (the "Company"), in connection with the preparation of a
registration statement on Form S-3 (the "Registration Statement"), filed with
the Securities and Exchange Commission (the "Commission") on the date hereof
pursuant to Rule 462(b) under the Securities Act of 1933, as amended (the
"Act"), relating to a registration statement on Form S-3 (File No. 333-20199)
previously filed by the Company and declared effective by the Commission (the
"Prior Registration Statement"). The Registration Statement relates to the
offering, as set forth in the Prior Registration Statement, the form of
prospectus contained therein (the "Prospectus") and one or more supplements to
the Prospectus (each, a "Prospectus Supplement"), of senior debt securities of
the Company, having an aggregate initial public offering price not to exceed
U.S. $600,000,000 ("Debt Securities"), on terms to be determined at the time of
the offering. The Debt Securities will be issued pursuant to a senior indenture
dated as of March 4, 1997 (the "Senior Indenture"), originally entered into by
the Company and JPMorgan Chase Bank (formerly known as The Chase Manhattan
Bank), as trustee, as the same has been and may hereafter be supplemented from
time to time, among other things at the time of and in connection with the
issuance of the Debt Securities. All capitalized terms which are not defined
herein shall have the meanings assigned to them in the Prior Registration
Statement.

            In arriving at the opinions expressed below, we have examined (i)
the Certificate of Incorporation and Bylaws of the Company, as amended to date,
(ii) the Prior Registration Statement and the Registration Statement, including
the form of prospectus included therein and the documents incorporated by
reference therein, (iii) the Prospectus, (iv) the Prospectus Supplement dated
June 4, 2002, (v) the Senior Indenture, as supplemented to date (the "Existing
Senior Indenture"), and (vi) the originals or copies certified or otherwise
identified to our satisfaction of such other instruments and certificates of
public officials, officers and representatives of the Company and other persons,
and we have made such investigations of law, as we have deemed appropriate as a
basis for the opinions expressed below.

            In rendering the opinions expressed below, we have assumed and have
not verified (i) the genuineness of the signatures on all documents that we have
examined, (ii) the legal capacity of all natural persons, (iii) the conformity
to the originals of all documents supplied to us as




certified or photostatic or faxed copies, (iv) the authenticity of the originals
of such documents, and (v) as to the forms of all documents in respect of which
forms were filed with the Commission as exhibits to the Prior Registration
Statement, the conformity in all material respects of such documents to the
forms thereof that we have examined. In conducting our examination of documents
executed by parties other than the Company, we have assumed that such parties
had the power, corporate or other, to enter into and perform all obligations
thereunder and have also assumed the due authorization by all requisite action,
corporate or other, and the due execution and delivery by such parties of such
documents and that such documents constitute valid and binding obligations of
such parties.

            In rendering the opinions expressed below with respect to the Debt
Securities, we have assumed that, as of the date of issuance, authentication and
delivery of any series thereof (i) the Certificate of Incorporation and By-laws
of the Company will not have been amended in any manner that would affect any
legal conclusion set forth herein, (ii) any supplemental indenture to the
Existing Senior Indenture pursuant to which such Debt Securities are issued will
comply with the Existing Senior Indenture as theretofore supplemented, and the
form and terms of such Debt Securities will comply with the Existing Senior
Indenture as then supplemented (including by such supplemental indenture) and
(iii) the form and terms of such Debt Securities, when established, will not
violate any applicable law, and (without limiting the generality of the
foregoing) Section 5-501.6.b of the New York General Obligations Law will apply
in the case of such Debt Securities. In addition, we have assumed the receipt by
each person to whom or for whose benefit a Debt Security is to be issued
(collectively, the "Holders") of a certificate for such Debt Security or the
receipt by the Depository Trust Company, acting as agent, on behalf of all
Holders of Debt Securities of the series of which such Debt Security is a part,
of a global security then evidencing all Debt Securities of such series, and the
issuance and sale of and payment for all Debt Securities in accordance with the
applicable purchase, underwriting or similar agreement approved by the Board of
Directors of the Company (the "Board"), the Prior Registration Statement and the
Registration Statement.

            Based on the foregoing, and subject also to the limitations and
other assumptions and qualifications set forth below, we are of the opinion
that, with respect to each series of Debt Securities to be issued under the
Existing Senior Indenture, as supplemented to the date of such issuance, when
(a) any applicable supplemental indenture to the Existing Senior Indenture (as
theretofore supplemented) has been duly authorized and validly executed and
delivered by the Company and the Trustee, (b) the Company has taken all
necessary corporate action to approve the issuance and terms of any such
applicable supplemental indenture and such series of Debt Securities, the terms
of the offering thereof and related matters and (c) the Debt Securities of such
series have been duly executed, authenticated, issued and delivered in
accordance with the terms of the Existing Senior Indenture (as then
supplemented) and the applicable definitive purchase, underwriting or similar
agreement approved by the Board, upon payment (or delivery) of the consideration
therefor provided for therein, the Debt Securities of such series will be
legally issued and will constitute valid and legally binding obligations of the
Company.

            The validity and enforceability of any of the obligations of the
Company in respect of the Debt Securities are subject to applicable bankruptcy,
insolvency (including, without limitation, all laws relating to fraudulent
transfer or conveyance), reorganization, moratorium and other




similar laws affecting creditors' rights generally and to general principles of
equity (regardless of whether enforcement is sought in a proceeding in equity or
at law). In addition, we express no opinion as to any provision of the Existing
Indenture that (a) relates to severability or separability or (b) relates to
choice of law to the extent, if any, it purports to require disregard of
mandatory choice of law rules.

            This opinion speaks as of its date and we undertake no, and hereby
disclaim any, duty to advise as to changes of fact or law coming to our
attention after the delivery hereof on such date. For the purposes of the
opinions expressed above, we have assumed that, at the time of the execution and
delivery of any applicable supplemental indenture and at the time of the
issuance, authentication and delivery of the Debt Securities of any series (a)
the Company will be validly existing in good standing under the law of the State
of Delaware, it will have full power and authority to execute and deliver and
perform its obligations under such supplemental indenture and Debt Securities,
and there shall have occurred no change in applicable law (statutory or
decisional), rule or regulation, or in any other relevant fact or circumstance,
that (in any such case) would adversely affect our ability to render at such
time an opinion containing the same legal conclusions herein set forth and
subject only to the same (or fewer) assumptions, limitations and qualifications
as are contained herein, and (b) (i) the Prior Registration Statement and the
Registration Statement, and any amendments thereto (including post-effective
amendments), will be effective, (ii) a Prospectus Supplement will have been
prepared and filed with the Commission describing the specific terms of the Debt
Securities offered thereby, (iii) all such Debt Securities will have been issued
and sold in compliance with applicable United States federal and state
securities laws and in the manner stated in the Prior Registration Statement and
the applicable Prospectus Supplement, and (iv) a definitive purchase,
underwriting or similar agreement with respect to such Debt Securities will have
been duly authorized and validly executed and delivered by the Company and the
other parties thereto.

            We express no opinion other than as to, and, to the extent relevant,
the federal laws of the United States of America and the laws of the State of
New York. We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to this firm under the heading
"Legal Matters" in the Prospectus Supplement. In giving this consent we do not
admit that we are "experts" under the Act, or the rules and regulations of the
Commission issued thereunder, with respect to any part of the Registration
Statement, including this exhibit. This opinion is rendered solely for your
benefit in connection with the above matter and may not be relied upon in any
manner by any other person or entity without our express written consent.

                                             Very truly yours,

                                             /s/ LOCKE LIDDELL & SAPP LLP