SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C.  20549
SCHEDULE 13G
(RULE 13D - 102)
INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO 13d-1(b), (c) AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO 13d-2(b)
(Amendment No. )*
Radius Health, Inc.
(Name of Issuer)
Common Stock, $.0001 par value
(Title of Class of Securities)
750469 20 7
(CUSIP Number)
January 13, 2016
(Date of Event which Requires Filing of this Statement)
Check the appropriate box to designate the rule pursuant to which this Schedule is filed:
[ ]            Rule 13d-1(b)
[x]            Rule 13d-1(c)
[ ]            Rule 13d-1(d)
*The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.
The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).


1.
NAMES OF REPORTING PERSONS
I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
   
 
Tourbillon Capital Partners, L.P.
   
2.
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
   
 
(a)    [x]
 
(b)    [ ]
   
3.
SEC USE ONLY
   
4.
CITIZENSHIP OR PLACE OF ORGANIZATION
   
 
Delaware
   
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:
   
5.
SOLE VOTING POWER
   
 
0
   
6.
SHARED VOTING POWER
   
 
2,333,876
   
7.
SOLE DISPOSITIVE POWER
   
 
0
   
8.
SHARED DISPOSITIVE POWER
   
 
2,333,876
   
9.
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
   
 
2,333,876
   
10.
CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9)
EXCLUDES CERTAIN SHARES    [ ]
   
11.
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
   
 
5.4%
   
12.
TYPE OF REPORTING PERSON
   
 
PN, IA



1.
NAMES OF REPORTING PERSONS
I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)
   
 
Jason H. Karp
   
2.
CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
   
 
(a)    [x]
 
(b)    [ ]
   
3.
SEC USE ONLY
   
4.
CITIZENSHIP OR PLACE OF ORGANIZATION
   
 
USA
   
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:
   
5.
SOLE VOTING POWER
   
 
0
   
6.
SHARED VOTING POWER
   
 
2,333,876
   
7.
SOLE DISPOSITIVE POWER
   
 
0
   
8.
SHARED DISPOSITIVE POWER
   
 
2,333,876
   
9.
AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
   
 
2,333,876
   
10.
CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9)
EXCLUDES CERTAIN SHARES    [ ]
   
11.
PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
   
 
5.4%
   
12.
TYPE OF REPORTING PERSON
   
 
IN



Item 1(a). Name of Issuer:
Radius Health, Inc. (the "Issuer")
Item 1(b). Address of Issuer's Principal Executive Offices:
950 Winter Street
Waltham, Massachusetts 02451

Item 2(a). Name of Persons Filing:
The names of the persons filing this statement on Schedule 13G are Tourbillon Capital Partners, L.P. ("Tourbillon Capital Partners") and Jason H. Karp (together, the "Reporting Persons"). Mr. Karp is the Chief Executive Officer of Tourbillon Capital Partners.
Item 2(b). Address of Principal Business Office or, if None, Residence:
The address of the principal business office of each of the Reporting Persons is 444 Madison Avenue, 26th Floor, New York, NY 10022.
Item 2(c). Citizenship:
Tourbillon Capital Partners is a Delaware limited partnership. Mr. Karp is a citizen of the United States of America.
Item 2(d). Title of Class of Securities:
Common Stock, $.0001 par value (the "Common Shares")
Item 2(e). CUSIP Number:
750469 20 7
Item 3. If This Statement is Filed Pursuant to Rule 13d 1(b), or 13d-2(b) or (c), Check Whether the Person Filing is a:
 
(a)
[ ]
Broker or dealer registered under Section 15 of the Exchange Act.
       
 
(b)
[ ]
Bank as defined in Section 3(a)(6) of the Exchange Act.
       
 
(c)
[ ]
Insurance company defined in Section 3(a)(19) of the Exchange Act.
       
 
(d)
[ ]
Investment company registered under Section 8 of the Investment Company Act.
       
 
(e)
[ ]
Investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E).
       
 
(f)
[ ]
Employee benefit plan or endowment fund in accordance with Rule 13d-1(b)(1)(ii)(F).
       
 
(g)
[ ]
Parent holding company or control person in accordance with Rule 13d-1(b)(1)(ii)(G).
       
 
(h)
[ ]
Savings association as defined in Section 3(b) of the Federal Deposit Insurance Act.
       
 
(i)
[ ]
Church plan that is excluded from the definition of an investment company under Section 3(c)(14) of the Investment Company Act;
       
 
(j)
[ ]
Non-U.S. institution in accordance with Section 240.13d-1(b)(1)(ii)(J).
       
 
(k)
[ ]
Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).  If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution: ____


Item 4. Ownership.
Provide the following information regarding the aggregate number and percentage of the class of securities of the Issuer.
(a) Amount beneficially owned:
As of the close of business on January 13, 2016, the Reporting Persons may be deemed to have  beneficially owned 2,333,876 Common Shares, including 741,000 shares underlying currently exercisable options.
(b) Percent of class:
The aggregate percentage of Common Shares reported owned by each person named herein is based upon 42,922,227 Common Shares outstanding as of October 30, 2015, which is the total number of Common Shares outstanding as reported in the Issuer's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 5, 2015. As of the close of business on January 13, 2016, the Reporting Persons may be deemed to have beneficially owned approximately 5.4% of Common Shares outstanding.
 (c) Number of shares as to which such person has:
(i) Sole power to vote or to direct the vote:
See Cover Pages Items 5-9.
 (ii) Shared power to vote or to direct the vote
See Cover Pages Items 5-9.
 (iii) Sole power to dispose or to direct the disposition of
See Cover Pages Items 5-9.
 (iv) Shared power to dispose or to direct the disposition of
See Cover Pages Items 5-9.
Item 5. Ownership of Five Percent or Less of a Class.
If this statement is being filed to report the fact that as of the date hereof the Reporting Persons have ceased to be the beneficial owner of more than five percent of the class of securities, check the following [  ].
Item 6. Ownership of More than Five Percent on Behalf of Another Person.
Not applicable.
Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company.
Not applicable.
Item 8. Identification and Classification of Members of the Group.
See Exhibit A.
Item 9. Notice of Dissolution of Group.
Not applicable.
Item 10. Certification.
By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.



SIGNATURES
After reasonable inquiry and to the best of its knowledge and belief, each of the undersigned certifies that the information with respect to it set forth in this statement is true, complete, and correct.
Dated: January 25, 2016
TOURBILLON CAPITAL PARTNERS, L.P.


By: /s/ Brian A. Kessler
       Brian A. Kessler,
       Chief Financial Officer



/s/ Jason H. Karp
Jason H. Karp





EXHIBIT A
JOINT FILING AGREEMENT
The undersigned hereby agree that the statement on Schedule 13G with respect to the Common Shares of Radius Health, Inc. dated January 25, 2016, and any amendments thereto signed by each of the undersigned shall be, filed on behalf of each of the undersigned pursuant to and in accordance with the provisions of Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended.
Dated: January 25, 2016

TOURBILLON CAPITAL PARTNERS, L.P.


By: /s/ Brian A. Kessler
       Brian A. Kessler,
       Chief Financial Officer



/s/ Jason H. Karp
Jason H. Karp