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): February 23, 2010

OPTIMER PHARMACEUTICALS, INC.

(Exact name of registrant as specified in its charter)

10110 Sorrento Valley Road, Suite C

San Diego, CA  92121

(Address of principal executive offices, including zip code)

Registrant’s telephone number, including area code: (858) 909-0736

N/A

(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:

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))

Forward-Looking Statements

This Form 8-K and the exhibit attached hereto contain forward looking statements that are based on current expectations, estimates, forecasts and projections about us, our future performance, our business or others on our behalf, our beliefs and our management’s assumptions. In addition, we, or others on our behalf, may make forward looking statements in press releases or written statements, or in our communications and discussions with investors and analysts in the normal course of business through meetings, webcasts, phone calls and conference calls. Words such as “expect,” “anticipate,” “will,” “could,” “would” “project,” “intend,” “plan,” “believe,” “predict,” “estimate,” “should,” “may,” “potential,” “continue,” “ongoing”, or variations of such words and similar expressions are intended to identify such forward looking statements. These forward-looking statements include, among others, statements about estimates regarding our cash position as of December 31, 2009, the submission of applications for and receipt of regulatory clearances and approvals, our expectations and plans regarding partnering, licensing, marketing and commercializing our product candidates, the progress, timing and results of clinical trials and research and development efforts involving our product candidates, the safety and efficacy of our product candidates, estimates of the potential markets for our product candidates, our expectations with regard to our intellectual property position, our plans to conduct future clinical trials or research and development efforts, estimates of the capacity of manufacturing and other facilities to support our products candidates, and our operating and growth strategies, our industry, our projected cash needs, liquidity and capital resources and our expected future revenues, operations and expenditures.  These statements are not guarantees of future performance and involve certain risks, uncertainties and assumptions that are difficult to predict. We describe our respective risks, uncertainties and assumptions that could affect the outcome or results of operations in this Form 8-K and our other filings with the Securities and Exchange Commission, or SEC. Our forward looking statements reflect our management’s beliefs and assumptions based on information available to our management at the time the statements are made. We caution you that actual outcomes and results may differ materially from what is expressed, implied or forecast by our forward looking statements. Except as required under the federal securities laws and the rules and regulations of the SEC, we do not have any intention or obligation to update publicly any forward looking statements after the distribution of this Form 8-K, whether as a result of new information, future events, changes in assumptions or otherwise.

Item 2.02               Results of Operations and Financial Condition.

Although we have not finalized our full financial results for the fiscal year ended December 31, 2009, we expect to report that we had approximately $38.2 million of cash, cash equivalents and short-term investments as of December 31, 2009.

The information contained in Item 2.02 of this Form 8-K is unaudited and preliminary, and does not present all information necessary for an understanding of our financial condition as of December 31, 2009 and our results of operations for the three months and year ended December 31, 2009. The audit of our consolidated financial statements for the year ended December 31, 2009 is ongoing and could result in changes to the information set forth above.  The information contained in Item 2.02 of this Form 8-K is being furnished and shall not be deemed to be “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liability of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, except as expressly set forth by specific reference in such a filing.

Item 8.01               Other Events.

We are filing certain information for the purpose of updating various aspects of the descriptions of our business and risk factors contained in our other filings with the SEC.  A copy of this additional disclosure about Optimer Pharmaceuticals, Inc. is attached as Exhibit 99.1 to this Form 8-K and incorporated herein by reference.

Item 9.01               Financial Statements and Exhibits.

(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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