Exhibit 5.2
May 4, 2009
RXi Pharmaceuticals Corporation
60 Prescott Street
Worcester, MA 01605
Re: Registration of Securities by RXi Pharmaceuticals Corporation
Ladies and Gentlemen:
This opinion is being furnished to you in connection with the Registration Statement on Form
S-3 (the Registration Statement), including the prospectus that is part of the Registration
Statement (the Prospectus), filed by RXi Pharmaceuticals Corporation, a Delaware corporation (the
Company), with the Securities and Exchange Commission (the SEC) under the Securities Act of
1933, as amended (the Securities Act) on or about the date hereof, for the registration for
resale of 500,000 shares (the Secondary Securities) of Common Stock, $0.0001 par value (Common
Stock), of RXi Pharmaceuticals Corporation, a Delaware corporation (the Company). We understand
that the Secondary Securities are being registered to permit the resale of such Common Stock by the
holder thereof from time to time after the effective date of the Registration Statement.
We have acted as counsel for the Company in connection with its preparation of the
Registration Statement. For purposes of this opinion, we have examined and relied upon such
documents, records, certificates and instruments as we have deemed necessary.
The opinions expressed below are limited to the Delaware General Corporation Law, including
the applicable provisions of the Delaware Constitution and the reported cases interpreting those
laws.
Based on the foregoing, we are of the opinion that the Secondary Securities have been duly
authorized and are validly issued, fully paid and non-assessable.
It is understood that this opinion is to be used only in connection with the offer and sale of
the Secondary Securities while the Registration Statement is in effect.
Very truly yours,
/s/ Ropes & Gray LLP
Ropes & Gray LLP