Oscient Pharmaceuticals Corporation (NASDAQ:OSCI) today announced that it cannot file on a timely basis its Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2009, which was due to be filed with the Securities and Exchange Commission by May 15, 2009. The Company does not expect that such filing will be made within five calendar days of the due date, as required for the extension provided by Rule 12b-25(b) promulgated under the Securities Exchange Act of 1934 (the “Exchange Act”).

The Company is unable to file its Quarterly Report on Form 10-Q by May 15, 2009 without unreasonable effort or expense as a result of the departure of certain employees, as well as the ongoing review of strategic alternatives previously expressed in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2008. The Company intends to complete the review of strategic alternatives as soon as possible, but it cannot at this time determine when its Quarterly Report on Form 10-Q for the quarter ended March 31, 2009 will be filed.

As noted in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2008, the Company believes that it has cash to continue current operations into the third quarter of 2009, unless it is able to raise additional capital and/or refinance or amend the terms of its capital structure. Additional financing may not be available, or, if available, may not be available on favorable terms. If the Company does not obtain adequate financing or is unable to pay its indebtedness as it becomes due, it may have to take other measures to significantly reduce expenses which will have a material adverse effect on its business and/or the Company may seek bankruptcy protection.

As a result of voluntary conversions of Company’s 12.50% Convertible Guaranteed Senior Notes due 2011 since the filing of the Company’s most recent Annual Report on Form 10-K, the Company has approximately 61 million common shares outstanding.

About Oscient Pharmaceuticals

Oscient Pharmaceuticals Corporation is a commercial-stage pharmaceutical company marketing two FDA-approved products in the United States: ANTARA^® (fenofibrate) capsules, a cardiovascular product and FACTIVE^® (gemifloxacin mesylate) tablets, a fluoroquinolone antibiotic. ANTARA is indicated for the adjunct treatment of hypercholesterolemia (high blood cholesterol) and hypertriglyceridemia (high triglycerides) in combination with diet.