Exhibit 5.1

	John Hancock Tower, 20th Floor 200 Clarendon Street Boston, Massachusetts  02116 Tel: +1.617.948.6000  Fax: +1.617.948.6001 www.lw.com
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	Milan

Radius Health, Inc.

201 Broadway, 6th Floor

Cambridge, MA, 02139

Re:Registration Statement on Form S-8 with respect to 3,597,889 shares
of Common Stock, par value $0.0001 per share

Ladies and Gentlemen:

We have acted as special counsel to Radius Health, Inc., a Delaware corporation (the “Company”), in connection with the preparation and filing by the Company with the Securities and Exchange Commission of a registration statement on Form S—8 (the “Registration Statement”) under the Securities Act of 1933, as amended (the “Securities Act”), relating to the issuance of up to 3,597,889 shares of the Company’s common stock, par value $0.0001 per share (the “Shares”), which may be issued pursuant to the Company’s 2003 Long-Term Incentive Plan and 2011 Equity Incentive Plan (collectively, the “Plans”).  This opinion is being furnished in connection with the requirements of Item 601(b)(5) of Regulation S-K under the Securities Act, and no opinion is expressed herein as to any matter pertaining to the contents of the Registration Statement or the prospectus forming a part thereof, other than as expressly stated herein with respect to the issuance of the Shares.

As such counsel, we have examined such matters of fact and questions of law as we have considered appropriate for purposes of this letter.  With your consent, we have relied upon the foregoing and upon certificates and other assurances of officers of the Company and others as to factual matters without having independently verified such factual matters.  We are opining herein only as to the General Corporation Law of the State of Delaware, as amended (the “DCGL”), and we express no opinion with respect to any other laws.

Subject to the foregoing and the other matters set forth herein, it is our opinion that, as of the date hereof, when either (i) the Shares shall have been duly registered on the books of the transfer agent and registrar therefor in the name or on behalf of the purchasers or (ii) certificates representing the Shares have been manually signed by an authorized officer of the transfer agent and registrar therefor, and have been issued by the Company against payment therefor in the circumstances contemplated by the Plans, assuming that the individual issuances, grants or awards under the Plans are duly authorized by all necessary corporate action of the Company and duly issued, granted or awarded and exercised in accordance with the requirements of law and the Plans (and the agreements and awards duly adopted

thereunder and in accordance therewith), the issue and sale of the Shares will have been duly authorized by all necessary corporate action of the Company, and the Shares will be validly issued, fully paid and non-assessable.  In rendering the foregoing opinion, we have assumed that the Company will comply with all applicable notice requirements regarding uncertificated shares provided for in the DGCL.

This opinion is for your benefit in connection with the Registration Statement and may be relied upon by you and by persons entitled to rely upon it pursuant to the applicable provisions of the Securities Act.  We consent to your filing this opinion as an exhibit to the Registration Statement.  In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Securities and Exchange Commission thereunder.

Very truly yours,

/s/ Latham & Watkins LLP