EXHIBIT 5.1

                      [PILLSBURY WINTHROP, LLP LETTERHEAD]

October 12, 2001


Cardima, Inc.
47266 Benicia Street
Fremont, California 94538


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 2,822,472 shares (the "Shares") of common stock, par value
$.001 per share (the "Common Stock"), of the Company and 1,693,481 shares (the
"Warrant Shares") of common stock issued or issuable upon exercise of certain
Redeemable Warrants to Purchase Common Stock of the Company and Warrants to
Purchase Common Stock issued by the Company on August 9, 10 and 13, 2001 (the
"Warrants"). 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."

     In connection with the foregoing, we have examined the Amended and Restated
Certificate of Incorporation, the Bylaws of the Company, certificates of
officers of the Company and public officials, and such other documentation as we
have deemed necessary or advisable in order to render the opinions expressed
herein.

     Based upon the foregoing, we are of the opinion that (1) the 2,822,472
shares of Common Stock (the "Shares") have been duly authorized and legally
issued and the Shares are fully paid and non-assessable and (2) the 1,693,481
Warrant Shares have been duly authorized and, when issued in connection with the
terms of the Warrants for the consideration set forth therein will be legally
issued, fully paid and non-accessible.

     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 WINTHROP LLP