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): December 28, 2011

(Exact name of registrant as specified in its charter)

(Address of principal executive offices, including zip code)

Registrant’s telephone number, including area code: (510) 580-8828

(Former name or former address, if changed since last report)

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):

Item 7.01. Regulation FD Disclosure.

On December 28, 2011, Opnext, Inc. issued a press release regarding the status of its contract manufacturing operations in Thailand following the severe flooding in Thailand. A copy of such press release is attached hereto as Exhibit 99.1.

The information contained in this Current Report, including Exhibit 99.1, shall not be incorporated by reference into any filing of the Company, whether made before or after the date hereof, regardless of any general incorporation language in such filing.

Item 9.01. Financial Statements and Exhibits.

INFORMATION CONCERNING FORWARD-LOOKING STATEMENTS — Certain of the statements contained in this report and Exhibit 99.1 attached hereto, including, without limitation, statements concerning the ongoing effects of flooding on operations at Fabrinet’s facilities in Thailand, the timing of the reinstatement of production for Opnext’s products, and Opnext’s ability to recover its losses through insurance or contractual protections, are forward-looking statements. Forward-looking statements are made based upon management’s good faith expectations and belief concerning future developments and their potential effect upon the Company and involve a number of risks and uncertainties that could cause actual results to differ materially from those anticipated by these forward-looking statements. Such risks and uncertainties include a variety of factors, some of which are beyond our control. In particular, such risks and uncertainties include, but are not limited to: uncertainty surrounding the ongoing impact of the flooding in Thailand; the possibility that Opnext’s customers could scale back or cancel their orders in light of perceived or real production and delivery constraints; the possibility that Opnext could encounter unexpected difficulties in replacing lost production capacity, including, but not limited to, difficulties sourcing the necessary equipment; and the possibility that available insurance and contractual protections might be inadequate to fully compensate Opnext for its losses. There can be no assurance that future developments will be in accordance with management’s expectations or that the effects of future developments on the Company will be those anticipated by management. Please refer to the publicly filed documents of the Company, including the Forms 10-Q and 10-K, for additional information about the risks and uncertainties related to the Company’s business that may affect the statements made in this Current Report on Form 8-K.

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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