EXHIBIT 5.1

                      [Letterhead of Dorsey & Whitney LLP]

                                   May 8, 2006

ATS Medical, Inc.
3905 Annapolis Lane, Suite 105
Minneapolis, Minnesota 55447

     RE: Registration Statement on Form S-3

Ladies and Gentlemen:

     We have acted as counsel to ATS Medical, Inc., a Minnesota corporation (the
"Company"), in connection with the registration under the Securities Act of
1933, as amended, of (1) up to $22,400,000 aggregate principal amount of 6%
Convertible Senior Notes due 2025 (the "Notes") issued pursuant to an Indenture,
dated as of October 7, 2005 and supplemented on October 13, 2005 (as
supplemented, the "Indenture"), by and between the Company and Wells Fargo Bank,
National Association, as trustee (the "Trustee"), which are convertible into
shares of common stock, $0.01 par value per share (the "Common Stock"), of the
Company (as converted, the "Conversion Shares"), (2) warrants (the "Warrants")
to purchase 1,344,000 shares of Common Stock (as exercised, the "Warrant
Shares"), and (3) 7,011,200 shares of Common Stock, which represent 105% of the
Conversion Shares and 105% of the Warrant Shares (the "Shares" and collectively
with the Notes and the Warrants, the "Securities"). The Securities are to be
offered and sold by certain securityholders of the Company (the "Selling
Securityholders"). In this regard, we have participated in the preparation of a
Registration Statement on Form S-3 registering the Securities for resale (such
Registration Statement, as it may be amended from time to time, is referred to
herein as the "Registration Statement").

     We have examined such documents and have reviewed such questions of law as
we have considered necessary and appropriate for the purposes of our opinions
set forth below. In rendering our opinions, we have assumed the authenticity of
all documents submitted to us as originals, the genuineness of all signatures
and the conformity to authentic originals of all documents submitted to us as
copies. We have also assumed the legal capacity for all purposes relevant hereto
of all natural persons and, with respect to all parties to agreements or
instruments relevant hereto other than the Company, that such parties had the
requisite power and authority (corporate or otherwise) to execute, deliver and
perform such agreements or instruments, that such agreements or instruments have
been duly authorized by all requisite action (corporate or otherwise), executed
and delivered by such parties and that such agreements or instruments are the
valid, binding and enforceable obligations of such parties. As to questions of
fact material to our opinions, we have relied upon certificates of officers of
the Company and of public officials.

     We are of the opinion that the Notes have been duly authorized, executed
and delivered in accordance with the Indenture, the Warrants have been duly
authorized, executed and delivered, and the Notes and the Warrants are the valid
and binding obligations of the Company, subject to the following:

          (a) We express no opinion as to (i) the effect of any bankruptcy,
     insolvency, reorganization, arrangement, fraudulent conveyance, moratorium
     or other similar laws relating to or affecting the rights of creditors
     generally, including, without limitation, laws relating to fraudulent
     transfers or conveyances and preferences, (ii) rights to indemnification
     and contribution contained in the Notes, the Indenture and the Registration
     Rights Agreement dated as of October 7, 2005 and amended on October 13,
     2005 among the Company and the Selling Securityholders, which may be
     limited by applicable law or equitable principles, or (iii) the effect of
     general principles of equity, including without limitation, concepts of
     materiality, reasonableness, good faith and fair dealing, and the possible
     unavailability of specific performance, injunctive relief or other
     equitable relief, and limitations on rights of acceleration regardless of
     whether considered in a proceeding in equity or at law.


          (b) Minnesota Statutes Section 290.371, Subd. 4, provides that any
     corporation required to file a Notice of Business Activities Report does
     not have a cause of action upon which it may bring suit under Minnesota law
     unless the corporation has filed a Notice of Business Activities Report and
     provides that the use of the courts of the State of Minnesota for all
     contracts executed and all causes of action that arose before the end of
     any period for which a corporation failed to file a required report is
     precluded. Insofar as our opinions may relate to the valid, binding and
     enforceable character of any agreement under Minnesota law or in Minnesota
     court, we have assumed that any party seeking to enforce such agreement has
     at all times been, and will continue at all times to be, exempt from the
     requirement of filing a Notice of Business Activities Report or, if not
     exempt, has duly filed, and will continue to duly file, all Notice of
     Business Activities Reports.

     We are of the further opinion that the Conversion Shares and the Warrant
Shares, when issued upon conversion of the Notes and exercise of the Warrants,
will be legally issued, fully paid and nonassessable.

     Our opinions expressed above are limited to the laws of the States of
Minnesota and New York.

     We hereby confirm to you that our opinion regarding the material U.S.
federal income tax consequences of the acquisition, ownership and disposition of
the Notes, the Warrants, the Conversion Shares and the Warrant Shares is set
forth in the Prospectus under the heading "Material U.S. Federal Income Tax
Considerations" subject to the limitations set forth therein.

     We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement, and to the reference to our firm under the headings
"Legal Matters" and "Material U.S. Federal Income Tax Considerations" in the
Prospectus constituting part of the Registration Statement.

                                        Very truly yours,


                                        /s/ Dorsey & Whitney LLP

TSH/SMD