SecProbe.io

January 22, 2013

Via E -mail
Jay R. Luly, Ph.D.
President and Chief Executive Officer
Enanta Pharmaceuticals, Inc.
500 Arsenal Street
Watertown, Massachusetts 02472

Re: Enanta  Pharmaceuticals, Inc.
Registration Statement on Form S -1
 Response Letter Dated January 15, 2013
  File No. 333 -184779

Dear Dr. Luly:

We have reviewed your correspondence dated January 15, 2013 and have the following
comment s.  Please respond to this letter by amending your registration statement or providing the
requested information , as appropriate .  If you do not believe th ese comment s apply to your facts
and circumstances or do not believe a n amendment is appropriate, plea se tell us why in a
response.

After reviewing any further amendment to your registration statement and the
information you provide in response to this comment, we may have additional comments.

Note 14: Stock -Based Awards

Stock Option Valuation , page  F-33

1. Please provide us a list of any equity issuances since the latest balance sheet date, the
related fair value of the stock, and any compensation or other costs that have been
recorded for those issuances.  Provide additional disclosure in the filing as appropriate.

2. Please disclose in the second paragraph of your proposed disclosure the risk -adjusted
discount rate and discount for the lack of marketability.

3. You have stated that you have used two valuation methods to estimate enterprise value:
the gui deline public company method and guideline transaction method under the market
approach and the discounted future cash flow method under the income approach.  Please
clarify in the filing how you used the market and income methods to ultimately determine
your enterprise method.  Confirm to us that the methods resulted in similar valuations and
if not, how you ultimately determined the enterprise valuation.  For the market approach,

Jay R. Luly, Ph.D.
Enanta Pharmaceuticals, Inc.
January 22, 2013
Page 2

 in which you used two methods to determine the valuation, clarify in the fil ing how both
methods were used in determining the ultimate valuation under the market approach.

We urge all persons who are responsible for the accuracy and adequacy of the disclosure
in the filing to be certain that the filing includes the information th e Securities Act of 1933 and
all applicable Securities Act rules require.   Since the company and its management are in
possession of all facts relating to a company’s disclosure, they are responsible for the accuracy
and adequacy of the disclosures they ha ve made.

Notwithstanding our comment, in the event you request acceleration of the effective date
of the pending registration statement please provide a written statement from the company
acknowledging that:

 should the Commission or the staff, acting p ursuant to delegated authority, declare the
filing effective, it does not foreclose the Commission from taking any action with respect
to the filing;

 the action of the Commission or the staff, acting pursuant to delegated authority, in
declaring the filing effective, does not relieve the company from its full responsibility for
the adequacy and accuracy of the disclosure in the filing; and

 the company  may not assert staff comments and the declaration of effectiveness as a
defense in any proceeding initiated by the Commission or any person under the federal
securities laws of the United States.

Jay R. Luly, Ph.D.
Enanta Pharmaceuticals, Inc.
January 22, 2013
Page 3

 Please refer to Rules 460 and 461 regarding requests for acceleration.  We will consider a
written request for acceleration of the effective date of the registration statement as confirmation
of the fact that those requesting acceleration are aware of thei r respective responsibilities under
the Securities Act of 1933 and the Securities Exchange Act of 1934 as they relate to the proposed
public offering of the securities specified in the above registration statement.  Please allow
adequate time for us to rev iew any amendment prior to the requested effective date of the
registration statement.

Sincerely,

 /s/ Jeffrey P. Riedler

Jeffrey Riedler
Assistant Director

cc: Nathaniel S. Gardiner, Esq.
 Stacie S. Aarestad, Esq.
Edwards Wildman Palmer LLP
111 Huntington Avenue
Boston, Massachusetts 02199