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                                                                     EXHIBIT 5.1

Patterson-UTI Energy, Inc.
4510 Lamesa Highway
P.O. Box 1416
Snyder, Texas 79550

Re: Adoption of Stock Option Plans of UTI Energy Corp.

Gentlemen:

         We have acted as counsel to Patterson-UTI Energy, Inc., a Delaware
corporation ("Patterson"), in connection with the registration under the
Securities Act of 1933 ("Securities Act") on Form S-8 (the "Registration
Statement") of 1,225,300 shares of the Company's common stock, par value $.01
per share ("Common Stock") covered by the following stock option plans: (i) the
Amended and Restated UTI Energy Corp. 1996 Employee Stock Option Plan; and (ii)
the Amended and Restated Non-Employee Director Stock Option Plan of UTI Energy
Corp. (collectively, the "Plans").

         In connection with the foregoing, we have examined: (a) the Amended and
Restated Certificate of Incorporation and the Bylaws of the Company, (b) the
Plans, (c) the Minutes of the Board of Directors of the Company, (d) the
applicable laws of the State of Delaware, and (e) a copy of the Registration
Statement and the exhibits and supplements thereto.

         Based on such examination, and having regard for such legal
considerations as we deem relevant, we are of the opinion that the Company is
authorized to issue and to sell the Common Stock; and the Common Stock, when
issued, delivered and paid for in accordance with the terms and conditions of
the appropriate Plan, will be legally issued, fully paid and nonassessable.

         We hereby consent (i) to be named in the Registration Statement, and in
the Prospectus that constitutes a part thereof, as attorneys passing upon the
validity of the issuance of the Common Stock on behalf of the Company, and (ii)
to the filing of this opinion as an exhibit to the Registration Statement.

         This opinion is to be used solely for the purpose of the registration
of the Common Stock and may not be used for any other purpose.



                                                Very truly yours,

                                                BAKER & HOSTETLER LLP