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                                                                     EXHIBIT 5.1

                       [HAYNES AND BOONE, LLP LETTERHEAD]


March 31, 2000



Bargo Energy Company
700 Louisiana, Suite 3700
Houston, Texas 77002

Gentlemen:

We have acted as counsel to Bargo Energy Company, a Texas corporation (the
"Company"), in connection with the preparation of the Registration Statement on
Form S-8 (the "Registration Statement") filed with the Securities and Exchange
Commission under the Securities Act of 1933, as amended, relating to the
registration of 660,000 shares of Common Stock, par value $0.01 per share (the
"Common Stock"), of the Company that may be issued pursuant to the terms of the
Future Petroleum Corporation 1993 Employee Incentive Plan (the "Plan").

In connection therewith, we have examined (i) the Certificate of Incorporation
and the Bylaws of the Company, each as amended; (ii) minutes and records of the
corporate proceedings of the Company with respect to the adoption of the Plan;
(iii) certificates of certain officers and directors of the Company; (iv) the
Plan; and (v) such other documents as we have deemed necessary for the
expression of the opinions contained herein.

In making the foregoing examination, we have assumed the genuineness of all
signatures and the authenticity of all documents submitted to us as originals,
and the conformity to original documents of all documents submitted to us as
certified or photostatic copies. Furthermore, we have assumed that prices paid
for shares of Common Stock will equal or exceed the par value per share of the
Common Stock. As to questions of fact material to this opinion, where such
facts have not been independently established, and as to the content and form
of the Certificate of Incorporation (as amended), Bylaws (as amended), minutes,
records, resolutions and other documents or writings of the Company, we have
relied, to the extent we deem reasonably appropriate, upon representations or
certificates of officers or directors of the Company and upon documents,
records and instruments furnished to us by the Company, without independent
check or verification of their accuracy.

Based upon the foregoing, and having due regard for such legal considerations
as we deem relevant, we are of the opinion that the 660,000 shares of Common
Stock covered by the Registration Statement, which may be issued from time to
time pursuant to the purchase of shares of Common Stock in accordance with the
terms of the Plan, have been duly authorized for issuance by the Company, and,
when so issued in accordance with the terms and conditions of the Plan, will be
validly issued, fully paid and nonassessable.

We hereby consent to the filing of this opinion with the Securities and
Exchange Commission as an exhibit to the Registration Statement.

                                        Very truly yours,

                                        /s/ HAYNES AND BOONE, LLP
                                        HAYNES AND BOONE, LLP