As filed with the Securities and Exchange Commission on September 29, 2017

Registration No. 333-               

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

FORM S-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

RITTER PHARMACEUTICALS, INC.

(Exact name of registrant as specified in its charter)

Ritter Pharmaceuticals, Inc.
1880 Century Park East #1000

Los Angeles, CA 90067

(310) 203-1000

(Address, including zip code, and telephone number,
including area code, of registrant’s principal executive office)

Michael D. Step

Chief Executive Officer

Ritter Pharmaceuticals, Inc.

1880 Century Park East #1000

Los Angeles, CA 90067

(310) 203-1000

(Name, address, including zip code, and telephone number,
including area code, of agent for service)

Copies to:

Approximate date of commencement of proposed sale to the public: As soon as practicable after this Registration Statement becomes effective.

If any of the Securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, as amended, check the following box: [  ]

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act Registration Statement number of the earlier effective Registration Statement for the same offering: [X]           333-219147

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, please check the following box and list the Securities Act Registration Statement number of the earlier effective Registration Statement for the same offering: [  ]

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act Registration Statement number of the earlier effective Registration Statement for the same offering: [  ]

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

CALCULATION OF REGISTRATION FEE

(1) Represents only the additional dollar amount of securities being registered and includes the additional dollar amount of securities that the underwriters have the option to purchase to cover over-allotments, if any. Does not include the securities that the registrant previously registered on the registration statement on Form S-1 (File No. 333-219147).

(2) Calculated in accordance with Rule 457(o) under the Securities Act of 1933, as amended. Based on the public offering price per share.

THIS REGISTRATION STATEMENT SHALL BECOME EFFECTIVE UPON FILING WITH THE U.S. SECURITIES AND EXCHANGE COMMISSION IN ACCORDANCE WITH RULE 462(B) UNDER THE SECURITIES ACT.

EXPLANATORY NOTE AND INCORPORATION BY REFERENCE

This Registration Statement is being filed with respect to the registration of additional shares of common stock, with par value of $0.001 per share, of Ritter Pharmaceuticals, Inc., a corporation organized under the laws of the State of Delaware (the “Registrant”), pursuant to Rule 462(b) under the Securities Act of 1933, as amended. The contents of the Registration Statement on Form S-1 (File No. 333-219147) filed by the Registrant with the Securities and Exchange Commission, as amended, declared effective on September 28, 2017, including exhibits and power of attorney thereto, are incorporated by reference in this Registration Statement.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the registrant has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized in the City of Los Angeles, California, on September 29, 2017.

Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed by the following persons in the capacities and on the date indicated.

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