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                                                                     EXHIBIT 5.1

                                  July 24, 2001

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

Re: Adoption of Stock Option Plans of Patterson-UTI Energy, Inc.

Gentlemen:

         We have acted as counsel to Patterson-UTI Energy, Inc., a Delaware
corporation ("Company"), in connection with the registration under the
Securities Act of 1933 ("Securities Act") on Form S-8 (the "Registration
Statement") and the Post-Effective Amendment No. 1 to the Registration Statement
of 3,612,579 shares of the Company's common stock, par value $.01 per share
("Common Stock"), covered by the following stock option plans: (i) the 1997
Stock Option Plan of DSI Industries, Inc.; and (ii) the Patterson-UTI Energy
Inc. Amended and Restated 1997 Long-Term Incentive Plan, as amended
(collectively, the "Plans").

         In connection with the foregoing, we have examined: (a) the 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,
Post-Effective Amendment No. 1 to the Registration Statement, and the exhibits
and supplements to each.

         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 Post-Effective Amendment No. 1 to
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 Post-Effective Amendment No. 1 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,

                                                     /s/ BAKER & HOSTETLER LLP