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                                                                     EXHIBIT 5.1

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

                                  June 11, 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 "Registration Statement") of the Company to be filed
with the Securities and Exchange Commission (the "Commission") under the
Securities Act of 1933, as amended (the "1933 Act"), for the sale in an
underwritten public offering of up to 2,000,000 shares of the Common Stock,
$0.01 par value (the "Common Stock") of the Company (the "Company Shares"), and
up to 250,000 shares of Common Stock issued to a selling stockholder (the
"Outstanding Shares") of the Company and up to 337,500 shares of Common Stock
subject to the underwriters' over-allotment option (the "Option Shares"). This
opinion is delivered to you in connection with the Registration Statement 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, (i)
the Company Shares and the Option Shares have been duly authorized and will,
upon sale and delivery


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MiniMed Inc.
June 11, 1999
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thereof and receipt by the Company of full payment therefor as set forth in the
Registration Statement, be validly issued, fully paid and nonassessable; and
(ii) the Outstanding 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
Registration Statement and to the reference to this firm under the caption
"Legal Matters" in the Prospectus which is a part of the Registration Statement.

                                    Very truly yours,

                                    GIBSON, DUNN & CRUTCHER LLP

RJS/HJH/SKH