Omeros Corporation Reports Fourth Quarter and Year-End 2014 Financial Results 4Q 2014 net loss of $20.7 million, or $0.61 per share SEATTLE, WA

Omeros Corporation Reports Fourth Quarter and Year-End 2014 Financial Results

4Q 2014 net loss of $20.7 million, or $0.61 per share

SEATTLE, WA March 16, 2015 Omeros Corporation (NASDAQ: OMER), a biopharmaceutical company committed to discovering, developing and

commercializing small-molecule and protein therapeutics for large-market as well as orphan indications targeting inflammation, coagulopathies and disorders of the central nervous system, today announced recent highlights and developments as well as

financial results for the fourth quarter and year ended December 31, 2014, which include:

many important achievements for Omeros, transitioning us from a solely R&D to a commercial company with FDA s approval of Omidria, said Gregory A. Demopulos, M.D., chairman and chief executive officer of Omeros. Receipt of

pass-through status from CMS, we expect, will accelerate our commercial success. The controlled launch of Omidria began in February and the feedback from those surgeons using Omidria has been uniformly positive. The broad launch of Omidria is

planned for early April, which will coincide nicely with the product s increased visibility at the annual meeting of the American Society of Cataract and Refractive Surgery later that month. Our pipeline programs also made substantial progress,

most notably resulting in positive preliminary data in the Phase 2 clinical trial evaluating OMS721, our proprietary MASP-2 antibody currently in development for the treatment of TMAs.

Fourth Quarter and Recent Highlights

For the quarter ended

December 31, 2014, Omeros reported a net loss of $20.7 million or $0.61 per share, including non-cash expenses of $4.2 million or $0.12 per share. This compares to a net loss of $1.8 million or $0.05 per share, including non-cash expenses of

$2.6 million or $0.09 per share, for the same period in 2013. The 2013 period includes a $12.5 million or $0.41 per share reduction of our net loss related to receiving a nonrecurring payment upon settlement of litigation. Excluding the litigation

settlement, the loss for the fourth quarter of 2013 would have been $14.3 million or $0.47 per share.

For the full year 2014, Omeros reported a net loss

of $73.7 million or $2.22 per share, including non-cash expenses of $11.7 million or $0.35 per share. This compares to a net loss of $39.8 million or $1.39 per share in 2013, including non-cash expenses of $10.6 million or $0.37 per share. Excluding

the litigation settlement, the 2013 net loss would have been $52.3 million or $1.83 per share.

Operating expenses for the three months ended

December 31, 2014 were $20.2 million compared to $14.1 million for the same period in 2013, an increase of $6.1 million. The increase was primarily related to preparing for the U.S. commercial launch of Omidria, to non-cash expenses related to

stock-based compensation, to increased employee costs and to the U.S. pediatric clinical trial evaluating Omidria, which began during 2014. These increased expenses were partially offset by lower clinical research and development expenses due to the

timing of clinical trials evaluating OMS824.

Operating expenses for the year ended December 31, 2014 were $70.5 million, an increase of $18.4 million

compared to $52.1 million in 2013. The 2014 increase related primarily to preparing for the U.S. commercial launch of Omidria, to clinical trials evaluating OMS824 and OMS721, to Phase 3 clinical trials for Omidria, and to increased employee costs

and non-cash expenses related to stock-based compensation. These increased expenses were partially offset by lower preclinical activity on the PDE7 program.

Revenue for the quarter ended December 31, 2014 was $180,000 compared to $169,000 for the same period in 2013. For the year ended December 31, 2014,

revenue was $539,000 compared to $1.6 million in 2013. The decrease for the full year 2014 was due to lower revenue recognized from the GPCR program funding agreements with Vulcan and LSDF, and the company will not recognize any additional revenue

under these agreements in future periods.

At December 31, 2014, the company had cash and cash equivalents and short-term investments of $6.9

million. In February 2015 the company sold 3,444,831 shares of common stock at a public offering price of $20.03 per share and sold pre-funded warrants to purchase up to 749,250 shares of common stock at a public offering price of $20.02 per warrant

share, each warrant share having an exercise price of $0.01. After deducting underwriting discounts and other offering expenses, Omeros received net proceeds of approximately $79.1 million.

For 2015, the company anticipates that

operating expenses will be in the $110 million to $120 million range with non-cash expenses of approximately $15 million. This guidance is largely based on the continued preparations for the full-scale U.S. launch of Omidria as well as the continued

development of the company s product pipeline.

Conference Call Details

To access the live conference call via phone, please dial (844) 831-4029 from the United States and Canada or (920) 663-6278 internationally. The participant

passcode is 1480892. Please dial in approximately 10 minutes prior to the start of the call. A telephone replay will be available for one week following the call and may be accessed by dialing (855) 859-2056 from the United States and Canada or

(404) 537-3406 internationally. The replay passcode is 1480892.

To access the live and subsequently archived webcast of the conference call, go to the

Company s website at www.omeros.com and go to Events under the Investors section of the website. Please connect to the website at least 15 minutes prior to the call to allow for any software download that may be necessary.

About Omeros Corporation

biopharmaceutical company committed to discovering, developing and commercializing small-molecule and protein therapeutics for large-market as well as orphan indications targeting inflammation, coagulopathies and disorders of the central nervous

system. Derived from its proprietary PharmacoSurgery platform, the company s first drug product, Omidria (phenylephrine and ketorolac injection) 1%/0.3%, has been approved by the

FDA for use during cataract surgery or intraocular lens replacement (ILR) to maintain pupil size by preventing intraoperative miosis (pupil constriction) and to reduce postoperative ocular pain. Omeros is completing preparations for a planned

full-scale U.S. product launch in early April 2015. Omidria is currently under review for marketing approval by the European Medicines Agency. Omeros has six clinical-stage development programs focused on: complement-related thrombotic

microangiopathies; Huntington s disease, schizophrenia, and cognitive impairment; addictive and compulsive disorders; and preventing problems associated with surgical procedures. In addition, Omeros 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, look forward to, 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 ability to begin broad U.S. commercial sales of Omidria (OMS302) in early April 2015, Omeros ability to

obtain regulatory approval for its Marketing Authorization Application in the EU for the commercialization of Omidria, Omeros unproven preclinical and clinical development activities,

regulatory oversight, product commercialization, intellectual property claims, competitive developments, litigation, and the risks, uncertainties and other factors described under the heading Risk Factors in the company s Annual

Report on Form 10-K filed with the Securities and Exchange Commission on March 16, 2015. 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.

Investor and Media Relations

CONSOLIDATED STATEMENTS OF OPERATIONS

(In thousands, except share and per share data)

CONSOLIDATED CONDENSED BALANCE SHEET DATA