Omeros Corporation Reports Third Quarter 2013 Financial Results Obtains Additional $17.4 Million in Cash in 4Q 2013 SEATTLE, WA

Omeros Corporation Reports Third Quarter 2013 Financial Results

Obtains Additional $17.4 Million in Cash in 4Q 2013

SEATTLE, WA November 7, 2013

Omeros Corporation (NASDAQ: OMER), a

clinical-stage biopharmaceutical company committed to discovering, developing and commercializing products targeting inflammation, coagulopathies and disorders of the central nervous system, today announced its financial results for the third

Throughout the third quarter of 2013, we continued to make significant strides in development across our pipeline, stated

Gregory A. Demopulos, M.D., chairman and chief executive officer of Omeros. For OMS302, the marketing applications were accepted for review by both the FDA and EMA, and the market launch is planned for the second half of 2014. Our OMS824

program for the treatment of cognitive disorders was granted orphan drug designation by the FDA, generated positive Phase 1 clinical trial results, began enrollment in a Phase 2 trial in patients with schizophrenia and is now initiating a Phase 2

trial in Huntington s disease. OMS721, our MASP-2 inhibitor, entered a Phase 1 clinical trial from which we reported positive data today, and a Phase 2 trial to evaluate the molecule s efficacy and safety in patients with thrombotic

microangiopathies is planned for early 2014. Preclinically, our GPCR platform continued to identify functionally active compounds against an unprecedented number of orphan receptors, and our addiction and high-risk bleeding programs advanced toward

the clinic. Following the close of the quarter, we added over $17 million to our balance sheet, positioning Omeros to execute on a series of value-driving milestones during the remainder of 2013 and well into 2014.

Third Quarter and Recent Highlights

Total operating expenses for the quarter ended September 30, 2013 were $13.6 million and included non-cash expenses of $3.2 million related to rent

expense and stock-based compensation. For the same period in 2012, total operating expenses were $14.5 million, which included non-cash rent and stock-based compensation expenses of $576,000.

The decrease in total operating expenses for the quarter ended September 30, 2013 compared to the prior year quarter is primarily due to a litigation

settlement expense of $3.95 million recorded in the same period in 2012, which was reimbursed by CCIC in the fourth quarter of 2012. For the quarter ended September 30, 2013, total (i.e., cash and non-cash) operating expenses, excluding the

litigation expense, increased by $3.1 million compared to the same period in 2012. The increase was primarily due to the non-cash rent and stock-based compensation expenses of $3.2 million in 3Q 2013 compared to $576,000 in 3Q 2012. The remaining

increases were related to conducting the company s Phase 1 clinical program evaluating OMS824, advancing our MASP-2 program, preparing the New Drug Application (NDA) and Marketing Authorization Application (MAA) for OMS302, planning for the

commercial launch of

OMS302 in the second half of 2014, and non-recurring legal expenses incurred in connection with the CCIC matter. These higher costs were partially offset by lower overall clinical trial expenses

related to the completion of the company s OMS302 Phase 3 clinical program in January 2013 and the completion of the company s first OMS103HP Phase 3 clinical trial in arthroscopic partial meniscectomy patients in December 2012.

Total revenue for the quarter ended September 30, 2013 was $196,000 compared to $1.4 million for the same period in 2012. This decrease was primarily due

to lower revenue recognized from the company s GPCR platform development funding agreement with Vulcan Inc. and its affiliate. While research continues under the company s GPCR program, no additional deferred revenue under the Vulcan

agreement remains to be recognized after the first quarter of 2013.

For the quarter ended September 30, 2013, Omeros reported a net loss of $13.9

million, or $0.46 per share, inclusive of the above-referenced $3.2 million of non-cash charges equaling $0.11 per share, compared to a net loss of $13.3 million, or $0.51 per share, inclusive of the above-referenced $576,000 of non-cash charges

equaling $0.02 per share, for the same period in 2012.

At September 30, 2013, Omeros had cash, cash equivalents and short-term investments of $9.0

million. On October 24, 2013, subsequent to the end of the quarter, Omeros received a payment of $12.5 million from CCIC pursuant to the terms of the settlement agreement. Omeros also received $4.9 million in net proceeds from the sale of

373,700 shares of its common stock, sold at an average price of $13.29 per share, pursuant to the company s at-the-market equity facility in October 2013.

About Omeros Corporation

Omeros is a clinical-stage

biopharmaceutical company committed to discovering, developing and commercializing small-molecule and protein therapeutics targeting inflammation, coagulopathies and disorders of the central nervous system. Derived from its proprietary

PharmacoSurgery platform, the Company s lead drug product, OMS302 for lens replacement surgery, is currently under review for marketing approval by both the US Food and Drug

Administration and the European Medicines Agency with commercial launch planned for the second half of 2014. Omeros five other clinical programs are focused on schizophrenia, Huntington s disease and cognitive impairment; addictive and

compulsive disorders; complement-related diseases; and preventing problems associated with surgical procedures. Omeros also has a proprietary GPCR platform, which is making available an unprecedented number of new GPCR drug targets and corresponding

compounds to the pharmaceutical industry for drug development.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the

Securities Exchange Act of 1934, which are subject to the safe harbor created by those sections for such statements. All statements other than statements of historical fact are forward-looking statements, which are often indicated by

terms such as anticipate, believe, could, estimate, expect, goal, intend, may, plan, potential, predict,

project, should, will, would and similar expressions. Forward-looking statements are based on management s beliefs and assumptions and on information available to management only as of the date of

this press release. Omeros actual results could differ materially from those anticipated in these forward-looking statements for many reasons, including, without limitation, risks associated with Omeros unproven preclinical and clinical

development activities, regulatory oversight, commercialization of its products, intellectual property claims and the risks, uncertainties and other factors described under the heading Risk Factors in the Company s Quarterly Report

on Form 10-Q filed with the Securities and Exchange Commission on August 9, 2013. Given these risks, uncertainties and other factors, you should not place undue reliance on these forward-looking statements, and the Company assumes no obligation

to update these forward-looking statements, even if new information becomes available in the future.

Jennifer Cook Williams

Cook Williams Communications, Inc.

Investor and Media Relations

CONSOLIDATED STATEMENTS OF OPERATIONS

(In thousands, except share and per share data)

CONSOLIDATED BALANCE SHEET DATA