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): May 9, 2013

OPKO Health, Inc.

(Exact Name of Registrant as Specified in Charter)

Registrant’s telephone number, including area code: (305) 575-4100

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:

On May 9, 2013, OPKO Health, Inc., a Delaware corporation (the “Company”) issued a press release announcing operating and financial highlights for the quarter ended March 31, 2013. A copy of the press release is attached hereto as Exhibit 99.1.

The information included herein and in Exhibit 99.1 shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934 (“Exchange Act”) or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933 or the Exchange Act, except as expressly set forth by specific reference in such a filing.

Additional Information About the PROLOR Biotech, Inc. (“PROLOR”) Transaction and Where to Find It

In connection with the proposed transaction, OPKO will file with the SEC a registration statement on Form S-4 that will include a joint proxy statement of OPKO and PROLOR and that will also constitute a prospectus of OPKO. The definitive joint proxy statement/prospectus will be mailed to stockholders of OPKO and PROLOR. STOCKHOLDERS OF OPKO AND PROLOR ARE URGED TO READ THE JOINT PROXY STATEMENT/PROSPECTUS WHEN THEY BECOME AVAILABLE AND ANY OTHER RELEVANT DOCUMENTS FILED WITH THE SEC, AS WELL AS ANY AMENDMENTS OR SUPPLEMENTS TO THOSE DOCUMENTS, BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION. Investors and security holders will be able to obtain free copies of the registration statement and the definitive joint proxy statement/prospectus (when available) and other documents filed with the SEC by OPKO and PROLOR through the website maintained by the SEC at www.sec.gov. Free copies of the registration statement and the definitive joint proxy statement/prospectus (when available) and other documents filed with the SEC can also be obtained by directing a request to Steven D. Rubin, Executive Vice President – Administration or Juan F. Rodriguez, Chief Financial Officer, at 305-575-4100.

This communication shall not constitute an offer to sell or the solicitation of an offer to sell or the solicitation of an offer to buy any securities, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of such jurisdiction. No offering of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the Securities Act of 1933, as amended.

(d) Exhibits.

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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.

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EXHIBIT INDEX

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