SecProbe.io

May 7, 2015

Via E -mail
Michael D. Step
Chief Executive Officer
Ritter Pharmaceuticals, Inc.
1801 Century Park East #1820
Los Angeles, CA 90067

Re: Ritter Pharmaceuticals, Inc.
Amendment No. 1 to Registration Statement on Form S -1
Filed April 24, 2015
  File No. 333 -202924

Dear Mr. Step :

We have reviewed your amended registration statement and your response letter dated
April 24, 2015 and have the following comments.  In some of our comments, we may ask you to
provide us with information so w e may better understand your disclosure.

Please respond to this letter by amending your registration statement and providing the
requested information.   If you do not believe our comments apply to your facts and
circumstances or do not believe an amendmen t is appropriate, please tell us why in your
response.

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

Prospectus Summary, page 2

1. We note your revised disclosure that you intend to conduct a Phase 2b/3 trial of RP -G28.
Please amend your disclosure in this section to include the following information
consistent with disclosure appearing elsewhere in your prospectus:

 Neither the FDA nor any other comparable governmental agency has considered your
Phase 2b/3 study or your current development plan for RP -G28, and you do not
intend to request a meeting with the FDA to discuss thes e matters;
 You have not consulted with the FDA about the intent to use abdominal pain as a
primary endpoint  for the Phase 2b/3 pivotal clinical trial ; and
 You will need to submit an IND supplement containing amended protocols for the
Phase 2b/3 adaptive trial  that must be approved by the FDA.

Michael D. Step
Ritter Pharmaceuticals, Inc.
May 7 , 2015
Page 2

 Dilution, page  47

2. It appears that historical book value per share at December 31, 2014 throughout this item
should be based on stockholders’ deficit of $14,495,042.   Please revise accordingly.

Management’s Discussion and Analysis of Financial Condition and Results of Operations
Critical Accounting Policies and Estimates
Significant factors, assumptions and methodologies used in determining the estimated fair value
of the Company’s common stock, page 55

3. Refer to your response to item 5 of your April 24, 2015 letter. P lease tell us the number
of shares used to arrive at the $1.048 per share value in connection with the December
2014 valuation, and how the number of shares was determined.

Clinical and Regulatory
Principal Component Analysis of Microbiome Shifts , Page 79

4. The illustration provided in Figure 3 contains text that is illegible.  Please revise this
figure accordingly.

Government Regulation and Product Approval , page 87

5. We note your disclosure with respect to adaptive seamless phase 2b/3 designs and that
the main statistical challenge in such a design is ensuring control of the type I error rate.
Please revise your disclosure to define the term “type 1 error rate.”  In a ddition, please
include a discussion as to how you will address this statistical challenge where you
discuss the design of your Phase 2b/3 trial for RP -G28 elsewhere in the prospectus.

You may contact Rolf Sundwall at (202) 551 -3105 or Jim Rosenberg at (202) 551 - 3679
if you have questions regarding comments on the financial statements and related matters.
Please contact Johnny Gharib at (202) 551 -3170, Bryan Pitko at (202) 551 -3203 or me at (202)
551-3715  with any other questions.

Sincerely,

 /s/ Bryan J. Pitko for

Jeffrey P. Riedler
Assistant Director

cc: Via E -mail
 Yvan -Claude Pierre, Esq.
 Reed Smith LLP

Michael D. Step
Ritter Pharmaceuticals, Inc.
May 7 , 2015
Page 3