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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1. Name and Address of Reporting Person * GALAKATOS NICHOLAS   2. Issuer Name and Ticker or Trading Symbol Radius Health, Inc. [RDUS] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT, 200 CLARENDON STREET, 54TH FLOOR 3. Date of Earliest Transaction (Month/Day/Year) 04/23/2013 (Street) BOSTON, MA 02116 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) ___ Form filed by One Reporting Person _X_ 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

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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

Series B Convertible Preferred Stock

(1)

04/23/2013

P

91,175 (2)

(1)

(1)

Common Stock

911,750

$ 61.42

0

I

See footnote (2)

Common Stock Warrant

$ 6.142

04/23/2013

P

227,939 (3)

04/23/2013

04/23/2018

Common Stock

227,939

$ 6.142

0

I

See footnote (3)

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
GALAKATOS NICHOLAS C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116		X
SIMON NICHOLAS J III C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116		X
WHEELER KURT C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116		X

Signatures

/s/ Nicholas Galakatos		04/30/2013
**Signature of Reporting Person		Date
/s/ Nicholas J. Simon, III		04/30/2013
**Signature of Reporting Person		Date
Kurt Wheeler		04/30/2013
**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)	Each share of Series B Convertible Preferred Stock has no expiration date and is convertible at any time, in whole or in part, at the election of the holder at a conversion rate of 10 shares of Common Stock for every 1 share of Series B Convertible Preferred Stock.
(2)	The shares are held as follows: 75,899 by MPM BioVentures III-QP, L.P. ("BV III QP"), 5,103 by MPM BioVentures III, L.P. ("BV III"), 1,468 by MPM Asset Management Investors 2003 BVIII LLC ("AM 2003"), 2,291 by MPM BioVentures III Parallel Fund, L.P. ("BV Parallel") and 6,414 by MPM BioVentures III GmbH & Co. Beteiligungs KG ("BV KG"). MPM BioVentures III GP, L.P. ("MPM III GP") and MPM BioVentures III LLC ("MPM III LLC") are the direct and indirect general partners of BV III QP, BV III, BV Parallel and BV KG. Luke Evnin, Ansbert Gadicke, Nicholas Galakatos, Dennis Henner, Nicholas Simon III, Michael Steinmetz and Kurt Wheeler are the Series A members of MPM III LLC and the managers of AM 2003. Each reporting person disclaims beneficial ownership of the securities reported herein except to the extent of his or its respective pecuniary interest therein.
(3)	The warrants are held as follows: 189,748 by BV III QP, 12,758 by BV III, 3,670 by AM 2003, 5,728 by BV Parallel and 16,035 by BV KG. Each reporting person disclaims beneficial ownership of the securities reported herein except to the extent of his or its respective pecuniary interest therein.
Remarks: See Form 4 for MPM BioVentures III LLC filed simultaneously herewith for additional members of this joint filing.

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