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 * Licari Philip R   2. Issuer Name and Ticker or Trading Symbol NxStage Medical, Inc. [NXTM] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) SVP & Chief Operating Officer (Last) (First) (Middle) C/O NXSTAGE MEDICAL, INC., 439 SOUTH UNION STREET, 5TH FLOOR 3. Date of Earliest Transaction (Month/Day/Year) 03/24/2006 (Street) LAWRENCE, MA 01843 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 03/24/2006   A   13,027 A (1) 13,027 D

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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)

$ 4.1

03/24/2006

D(2)

208,962

(2)

10/24/2014

Common Stock

208,962

(2)

0

D

Stock Option (right to buy)

$ 5.47

03/24/2006

A(2)

208,962

(2)

10/24/2014

Common Stock

208,962

(2)

208,962

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Licari Philip R C/O NXSTAGE MEDICAL, INC. 439 SOUTH UNION STREET, 5TH FLOOR LAWRENCE, MA 01843			SVP & Chief Operating Officer

Signatures

/s/ Winifred L. Swan, Attorney-in-fact for Philip R. Licari		03/28/2006
**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)	On March 24, 2006, the issuer agreed to cancel an option to purchase 208,962 shares of common stock at $4.10 per share granted to the reporting person on October 25, 2004. In exchange for the cancelled option, the reporting person received a new option to purchase 208,962 shares of common stock at an exercise price of $5.47 and 13,027 shares of restricted stock.
(2)	The two reported transactions involved an amendment of an outstanding stock option resulting in the deemed cancellation of the "old" option and the grant of a replacement option. The option was originally granted on October 25, 2004 and provided for vesting as to 25% of the shares on the first anniversary of the grant date and as to the remainder in 36 equal monthly installments.

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