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 *
MPM BIOVENTURES III LLC
  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 91,175 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 $ 6.142 227,939 I See footnote (3)

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
MPM BIOVENTURES III LLC
C/O MPM ASSET MANAGEMENT
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116
    X    
MPM BIOVENTURES III PARALLEL FUND, L.P.
C/O MPM ASSET MANAGEMENT
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116
    X    
MPM BIOVENTURES III GMBH & CO. Beteiligungs KG
C/O MPM ASSET MANAGEMENT
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116
    X    
MPM BIOVENTURES III GP L.P.
C/O MPM ASSET MANAGEMENT
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116
    X    
MPM ASSET MANAGEMENT INVESTORS 2003 BVIII LLC
C/O MPM ASSET MANAGEMENT
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116
    X    
MPM BIOVENTURES III-QP L.P.
C/O MPM ASSET MANAGEMENT
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116
    X    
HENNER DENNIS
C/O MPM ASSET MANAGEMENT
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116
    X    
STEINMETZ MICHAEL
C/O MPM ASSET MANAGEMENT
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116
    X    
MPM BIOVENTURES III L.P.
C/O MPM ASSET MANAGEMETN
200 CLARENDON STREET, 54TH FLOOR
BOSTON, MA 02116
    X    

Signatures

 /s/ Luke Evnin, Series A Member of MPM BioVentures III LLC   04/30/2013
**Signature of Reporting Person Date

 /s/ Luke Evnin, Series A Member of MPM BioVentures III LLC, the general partner of MPM BioVentures III GP, L.P., the general partner of MPM BioVentures III Parallel Fund, L.P.   04/30/2013
**Signature of Reporting Person Date

 /s/ Luke Evnin, Series A Member of MPM BioVentures III LLC, the general partner of MPM BioVentures III GP, L.P., in its capacity as the Managing Limited Partner of MPM BioVentures III GmbH & Co. Beteiligungs KG   04/30/2013
**Signature of Reporting Person Date

 /s/ Luke Evnin, Series A Member of MPM BioVentures III LLC, the general partner of MPM BioVentures III GP, L.P.   04/30/2013
**Signature of Reporting Person Date

 /s/ Luke Evnin, member of MPM Asset Management Investors 2003 BVIII LLC   04/30/2013
**Signature of Reporting Person Date

 /s/ Luke Evnin, Series A Member of MPM BioVentures III LLC, the general partner of MPM BioVentures III GP, L.P., the general partner of MPM BioVentures III-QP, L.P.   04/30/2013
**Signature of Reporting Person Date

 /s/ Dennis Henner   04/30/2013
**Signature of Reporting Person Date

 /s/ Michael Steinmetz   04/30/2013
**Signature of Reporting Person Date

 /s/ Luke Evnin, Series A Member of MPM BioVentures III LLC, the general partner of MPM BioVentures III GP, L.P., the general partner of MPM BioVentures III, L.P.   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 Nicholas Galakatos filed simultaneously herewith for additional members of this joint filing.

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