As filed with the Securities and Exchange Commission on January 17, 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

ENTEROMEDICS INC.

(Exact name of registrant as specified in its charter)

2800 Patton Road

St. Paul, Minnesota 55113

(651) 634-3071

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

Dan W. Gladney

Chief Executive Officer

EnteroMedics Inc.

2800 Patton Road

St. Paul, Minnesota 55113

(651) 634-3003

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

with copies to:

Approximate date of commencement of proposed sale to the public: As soon as practicable after this Registration Statement is declared 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, 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.  ☒ (File No. 333-213704)

If this Form is a post-effective amendment filed pursuant to Rule 462(c) 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.  ☐

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, or a smaller reporting company. See definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act:

CALCULATION OF REGISTRATION FEE

This Registration Statement shall become effective upon filing in accordance with Rule 462(b) under the Securities Act of 1933.

EXPLANATORY NOTE

This 462(b) Registration Statement relates to the public offering of Class A Units and Class B Units (the “Offering”) contemplated by the Registration Statement on Form S-1 (File No. 333-213704), which was initially filed with the Securities and Exchange Commission (the “SEC”) on September 20, 2016, and which, as amended, was declared effective by the SEC on January 17, 2017 (the “Prior Registration Statement”). This Registration Statement on Form S-1 is being filed pursuant to Rule 462(b) under the Securities Act of 1933, as amended, for the purposes of registering additional securities of the same class as were included in the Prior Registration Statement, representing an increase in the maximum aggregate offering price by $1,749,150. The contents of the Prior Registration Statement and all exhibits thereto are hereby incorporated by reference.

The required opinion and consents are listed on an Exhibit Index attached hereto and filed herewith.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in St. Paul, Minnesota on January 17, 2017.

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons in the capacities held on the dates indicated.