UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the
Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): June 30, 2016

TESARO, Inc.

(Exact name of registrant as specified in its charter)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

o       Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o       Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o       Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o       Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

TESARO, Inc., a Delaware corporation (the “Company”), filed a prospectus supplement to its automatic shelf registration statement on Form S-3 (File No. 333-212324) on June 30, 2016 covering the resale of shares (the “Shares”) of the Company’s common stock issued in connection with the Company’s private placement of common stock that closed on March 18, 2016.

In connection with the resale of the Shares, the Company is filing the opinion of Hogan Lovells US LLP as Exhibit 5.1 to this Current Report on Form 8-K.

(d)           Exhibits.

2

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Dated:  June 30, 2016

3

EXHIBIT INDEX

4