Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
Martin David
   2. Issuer Name and Ticker or Trading Symbol
Cardiovascular Systems Inc [CSII] 		5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
President and CEO
(Last)
(First)
(Middle)
651 CAMPUS DRIVE		 3. Date of Earliest Transaction (Month/Day/Year)
04/21/2010
(Street)

ST. PAUL, MN 55112		 4. If Amendment, Date Original Filed(Month/Day/Year)
 6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)		 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)		 4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)		 5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)		 6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)		 7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Common Stock               168,311 (1) D  

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)		 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)		 5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)		 6. Date Exercisable and Expiration Date
(Month/Day/Year)		 7. Title and Amount of Underlying Securities
(Instr. 3 and 4)		 8. Price of Derivative Security
(Instr. 5)		 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)		 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)		 11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Stock Option (right to buy) $ 8.83 04/21/2010   D(2)     71,170   (2) 07/16/2011 Common Stock 71,170 $ 0 0 D  
Stock Option (right to buy) $ 8.83 04/21/2010   A(2)   71,170     (2) 07/16/2016 Common Stock 71,170 $ 0 71,170 D  
Stock Option (right to buy) $ 8.83 04/21/2010   D(3)     38,820   (3) 08/14/2011 Common Stock 38,820 $ 0 0 D  
Stock Option (right to buy) $ 8.83 04/21/2010   A(3)   38,820     (3) 08/14/2016 Common Stock 38,820 $ 0 38,820 D  
Stock Option (right to buy) $ 8.83 04/21/2010   D(4)     349,380   (4) 02/14/2012 Common Stock 349,380 $ 0 0 D  
Stock Option (right to buy) $ 8.83 04/21/2010   A(4)   349,380     (4) 02/14/2017 Common Stock 349,380 $ 0 349,380 D  
Stock Option (right to buy) $ 7.9               (5) 06/11/2017 Common Stock 90,580   90,580 D  
Stock Option (right to buy) $ 12.15               (6) 12/11/2017 Common Stock 242,625   242,625 D  
Stock Option (right to buy) $ 8.75               (7) 03/01/2019 Common Stock 32,350   32,350 D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
Martin David
651 CAMPUS DRIVE
ST. PAUL, MN 55112		   X     President and CEO  

Signatures

 /s/ John R. Remakel as Attorney-in-Fact for David L. Martin pursuant to Power of Attorney previously filed.   04/23/2010
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) Includes 6,007 shares acquired through the Issuer's Employee Stock Purchase Plan on December 31, 2009.
(2) The two reported transactions involved an amendment of an outstanding option, resulting in the deemed cancellation of the "old" option and the grant of a replacement option. The option was originally granted on July 17, 2006 and is fully exercisable.
(3) The two reported transactions involved an amendment of an outstanding option, resulting in the deemed cancellation of the "old" option and the grant of a replacement option. The option was originally granted on August 15, 2006 and is fully exercisable.
(4) The two reported transactions involved an amendment of an outstanding option, resulting in the deemed cancellation of the "old" option and the grant of a replacement option. The option was originally granted on February 15, 2007 and is fully exercisable.
(5) Exercisable: 30,194 on 6/12/08 and 30,193 on 6/12/09 and 6/12/10.
(6) Exercisable: 121,313 on 2/25/10 and 121,312 on 2/25/11.
(7) Exercisable: 16,175 on 3/2/10 and 3/2/11.

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