EXHIBIT 5.1

                        PILLSBURY MADISON & SUTRO LLP
                             2250 Hanover Street
                         Palo Alto, California 94304

                                 May 1, 2000

Cardima, Inc.
47266 Benicia Street
Fremont, CA 94538

        Re: Registration Statement on Form S-3

Ladies and Gentlemen:

        We are acting as counsel for Cardima, Inc., a Delaware corporation
(the "Company"), in connection with the registration under the Securities Act
of 1933, as amended, of 6,066,111 shares of Common Stock, par value $.001 per
share (the "Common Stock"), of the Company.  In this regard we have
participated in the preparation of a Registration Statement on Form S-3
relating to such shares of Common Stock.  Such Registration Statement, as
amended, is herein referred to as the "Registration Statement."

        We are of the opinion that 4,899,856 shares of the Common Stock has
been duly authorized and issued by the Company and is fully paid and
nonassessable.  The remaining 1,166,255 shares of the Common Stock have been
duly authorized and, when issued by the Company and paid for, will be legally
issued, fully paid and nonassessable.

        We hereby consent to the filing of this opinion as Exhibit 5.1 to the
Registration Statement and to the use of our name under the caption "Legal
Matters" in the Registration Statement and in the Prospectus included therein.

                                        Very truly yours,

                                        /s/ Pillsbury Madison & Sutro LLP