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                                                                     EXHIBIT 5.1





                               February 20, 1998

Securities and Exchange Commission
Judiciary Plaza
450 Fifth Street, N.W.
Washington, D.C. 20549

     Re:  Key Energy Group, Inc. - Registration Statement on Form S-8

Ladies and Gentlemen:

     We have acted as counsel to Key Energy Group, Inc., a Maryland corporation
(the "Company"), in connection with the registration on Form S-8 under the
Securities Act of 1933, as amended, of 3,000,000 shares (the "Shares") of the
Company's common stock, par value $.10 per share (the "Common Stock"). In such
capacity, we have examined the Amended and Restated Articles of Incorporation,
the bylaws and corporate proceedings of the Company, and based on such
examinations, and having regard for applicable legal principles, it is our
opinion that the Shares to be offered and sold pursuant to the Registration
Statement will be validly issued, fully paid and nonassessable outstanding
shares of Common Stock.

     We consent to the use of this opinion as an exhibit to the Registration
Statement and to the reference to our firm in the Registration Statement.

                                        Very truly yours,



                                        /s/ Porter & Hedges, L.L.P.
                                        Porter & Hedges, L.L.P.