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                                                                     EXHIBIT 5.1

                                 HELEN W. MELMAN
                                 ATTORNEY AT LAW

                         1299 OCEAN AVENUE, FOURTH FLOOR
                         SANTA MONICA, CALIFORNIA 90401

                            TELEPHONE (310) 458-6900
                            FACSIMILE (310) 394-4759

                                 August 29, 1997

Diagnostic Products Corporation
5700 West 96th Street
Los Angeles, CA 90045


        Re:     Registration Statement on Form S-8
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Gentlemen:

        Diagnostic Products Corporation, a California corporation (the
"Company"), proposes to issue and sell up to 1,000,000 shares of its Common
Stock, no par value (the "Shares"), upon the exercise of stock options granted
and to be granted from time to time under the Company's 1997 Stock Option Plan
(the "Plan"). The Shares are being registered on a Registration Statement on
Form S-8 under the Securities Act of 1933, as amended (the "Act"), to be filed
with the Securities and Exchange Commission on or about August 29, 1997.

        In connection with rendering the opinion hereinafter expressed, I have
examined originals, certified copies or other copies identified to my
satisfaction of the following documents and instruments:

        1.      Articles of Incorporation of the Company, as amended to date;

        2.      Bylaws of the Company, as amended to date;

        3.      Certain minutes of meetings of the Board Directors and
                Shareholders of the Company;

        4.      The Plan;

        5.      The Registration Statement, together with the exhibits to be
                filed in connection therewith, in the form to be filed with the
                Commission; and

        6.      The documents to be delivered to the holders of stock options
                which will constitute the prospectus under Section 10(a) of the
                Act.



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HELEN W. MELMAN
ATTORNEY AT LAW

        August 29, 1997
        Diagnostic Products Corporation
        5700 West 96th Street



                I have obtained from public officials and from officers of the
        Company and examined originals or copies, identified to my satisfaction,
        of such other certificates, agreements and other assurances as I
        consider necessary for the purpose of rendering the opinion hereinafter
        expressed.

                I have additionally consulted with officers and representatives
        of the Company and have obtained such representations with respect to
        matters of fact as I deem necessary or advisable. I have not necessarily
        independently verified the content of the factual statements made to me
        in connection therewith, nor the veracity of such representations, but I
        have no reason to doubt their truth or accuracy.

                Based on the foregoing, it is my opinion that the Shares, when
        issued, sold and paid for in accordance with the terms of the Plan, will
        be duly and validly issued, fully paid and non-assessable.

                I hereby consent to this opinion being filed as an exhibit to
        the Registration Statement. In giving this consent, I do not admit that
        I am in the category of persons whose consent is required under Section
        7 of the Act or the rules and regulations of the Commission thereunder.


                                        Very truly yours,

                                        /S/ HELEN W. MELMAN
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                                        Helen W. Melman