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                                                                     EXHIBIT 5.1

                          GIBSON, DUNN & CRUTCHER LLP
                             333 South Grand Avenue
                       Los Angeles, California 90071-3197
                            Telephone: (213) 229-7000
                           Telecopier: (213) 229-7520

                                  June 29, 1999


(213) 229-7000                                                     C 62416-00001

MiniMed Inc.
12744 San Fernando Road
Sylmar, California  91342

Ladies and Gentlemen:

      We have acted as counsel to MiniMed Inc., a Delaware corporation (the
"Company"), in connection with the preparation and filing of the Registration
Statement on Form S-3 (the "462(b) Registration Statement") of the Company to be
filed with the Securities and Exchange Commission (the "Commission") under the
Securities Act of 1933, as amended, for the registration of an additional 50,000
shares of Common Stock $0.01 par value (the "Common Stock") of the Company
issued to a selling stockholder (the "Shares") and up to 7,500 shares of Common
Stock subject to the underwriters' over-allotment option (the "Option Shares").
The Shares and the Option Shares are to be offered for sale to the public
together with Common Stock of the Company registered pursuant to the Company's
Registration Statement on Form S-3 (No. 333-80527) (the "Prior Registration
Statement"). This opinion is delivered to you in connection with the 462(b)
Registration Statement for the registration of the Shares and Option Shares on
Form S-3 for the aforementioned sales.

      In rendering the opinion set forth herein, we have made such
investigations of fact and law, and examined such documents and instruments, or
copies thereof established to our satisfaction to be true and correct copies
thereof, as we have deemed necessary under the circumstances.

      Based upon the foregoing and such other examination of law and fact as we
have deemed necessary, and in reliance thereon, we are of the opinion that


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MiniMed Inc.
June 29, 1999
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the Shares and the Option Shares are duly authorized, validly issued, fully paid
and nonassessable.

      The Company is a Delaware corporation. We are not admitted to practice in
Delaware. However, we are generally familiar with the Delaware General
Corporation Law and have made such review thereof as we consider necessary for
the purpose of this opinion. Subject to the foregoing, this opinion is limited
to Delaware, California and federal law.

      We hereby consent to the filing of this opinion as an exhibit to the
462(b) Registration Statement and to the reference to this firm under the
caption "Legal Matters" in the Prospectus included in the Prior Registration
Statement.

                                    Very truly yours,

                                    GIBSON, DUNN & CRUTCHER LLP

RJS/HJH/SKH