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                                                                     EXHIBIT 5.1

                             Andrews & Kurth L.L.P.
                             600 Travis, Suite 4200
                              Houston, Texas 77002

                                  May 30, 2001


Board of Directors
TETRA Technologies, Inc.
25025 I-45 North
The Woodlands, Texas 77380

Gentlemen:

         We have acted as counsel to TETRA Technologies, Inc., a Delaware
corporation (the "Company"), in connection with the Company's Registration
Statement on Form S-8 (the "Registration Statement") relating to the
registration under the Securities Act of 1933, as amended, of the issuance of
(i) an additional 950,000 shares (the "1990 Plan Shares") of the Company's
common stock, $0.01 par value (the "Common Stock"), pursuant to the Company's
1990 Stock Option Plan, as amended (the "1990 Plan") and (ii) an additional
500,000 shares (together with the 1990 Plan Shares, the "Shares") of Common
Stock pursuant to the Company's 1996 Stock Option Plan for Nonexecutive
Employees and Consultants (the "1996 Plan").

         In connection herewith, we have examined copies of such statutes,
regulations, corporate records and documents, certificates of public and
corporate officials and other agreements, contracts, documents and such other
instruments as we have deemed necessary as a basis for the opinion hereinafter
expressed. In such examination, we have assumed the genuineness of all
signatures, the authenticity of all documents submitted to us as originals and
the conformity with the original documents of all documents submitted to us as
copies. We have also relied, to the extent we deem such reliance proper, upon
information supplied by officers and employees of the Company with respect to
various factual matters material to our opinion.

         Based upon the foregoing and subject to the limitations and exceptions
set forth below, we are of the opinion that the Shares have been duly
authorized, and that such Shares will, when issued in accordance with the terms
of the 1990 Plan and 1996 Plan, respectively, be duly authorized, fully paid and
validly issued.

            We hereby consent to the use of this opinion as Exhibit 5.1 to the
Registration Statement and to the reference to our firm name under the caption
"Exhibits" therein. In giving this consent, we do not thereby admit that we are
within the category of persons whose consent is required under Section 7 of the
Securities Act or the rules and regulations of the Securities and Exchange
Commission promulgated thereunder, or Item 509 of Regulation S-K.

         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. We express no opinion other
than as to the General Corporation Law of the State of Delaware (including the
applicable provisions of the Delaware Constitution and the reported judicial
decisions interpreting those laws) and, to the extent applicable, the federal
laws of the United States of America. 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,