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                                                                     EXHIBIT 5.1

                  [KUMMER KAEMPFER BONNER & RENSHAW LETTERHEAD]

January 3, 2001

Watson Pharmaceuticals, Inc.
311 Bonnie Circle
Corona, CA 92880

Ladies and Gentleman:

            We have acted as counsel for Watson Pharmaceuticals, Inc., a Nevada
corporation (the "Company"), in connection with the registration statement on
Form S-3 ("Registration Statement") to be filed by the Company with the
Securities and Exchange Commission covering 2,839,306 shares of the Company's
common stock, $0.0033 par value per share ("Common Stock"), issued in connection
with (i) the acquisition of all outstanding shares of Makoff R&D Laboratories,
Inc., and (ii) the Stock Acquisition Agreement dated October 16, 2000 with
Jerome Stevens Pharmaceuticals, Inc.

            In rendering this opinion, we have examined and relied on the
following documents: (i) the Company's Articles of Incorporation, as amended,
and Bylaws, as amended, (ii) the resolutions adopted by the Board of Directors
of the Company on October 3, 2000, (iii) the Registration Statement, and (iv)
such other documents, legal opinions and precedents, corporate and other records
of the Company, and certificates of public officials and officers of the Company
that we have deemed necessary or appropriate to provide a basis for the opinion.

            Based upon and subject to the foregoing, in our opinion, the shares
of Common Stock of the Company which are being offered and sold by the Company
pursuant to the Registration Statement, when sold in the manner and for the
consideration contemplated by the Registration Statement, will be legally
issued, fully paid and non-assessable.

            We consent to the filing of this opinion as an Exhibit to the
Registration Statement and to the reference to our firm under the heading "Legal
Matters."

                                            Very truly yours,

                                            KUMMER KAEMPFER BONNER & RENSHAW