Sirna Therapeutics, Inc. To Webcast Presentation At The CIBC World Markets Biotechnology & Specialty Pharmaceuticals Conference

SAN FRANCISCO, March 28 /PRNewswire-FirstCall/ -- Sirna Therapeutics, Inc. (“Sirna”) , a leading RNAi therapeutics company, announced today that Howard W. Robin, Sirna’s President and Chief Executive Officer is scheduled to give a company presentation at the CIBC World Markets Biotechnology & Specialty Pharmaceuticals Conference, on Tuesday, April 4, 2006 at 1:15 p.m. ET (10:15 a.m. PT) at the Millennium Broadway Hotel in New York City.

A live audio and visual webcast of the presentation will be available at the Company’s corporate web site at www.sirna.com. Participants are urged to log on to the web site 15 minutes prior to the scheduled start time to download and install any necessary audio software. The webcast will also be archived approximately three hours after the live event and will be available for 30 days, through July 3, 2006.

About Sirna Therapeutics

Sirna Therapeutics is a clinical-stage biotechnology company developing RNAi-based therapies for serious diseases and conditions, including age-related macular degeneration (AMD), hepatitis B and C, dermatology, asthma, Huntington’s disease, diabetes and oncology. Sirna Therapeutics has presented interim Phase 1 clinical trial data for its most advanced compound, Sirna-027, a chemically optimized siRNA targeting the clinically validated vascular endothelial growth factor pathway to treat AMD. Sirna-027, which has been partnered with Allergan, Inc., has demonstrated that it is safe and well tolerated with 25 of 26 patients showing visual acuity stabilization and 23% of those patients experiencing clinically significant improvement in visual acuity eight weeks after a single injection. In addition, Sirna recently announced that it has selected Sirna-034, a systemically delivered, optimized siRNA compound, as its candidate for advancement to human clinical testing against Hepatitis C virus. Sirna has a leading intellectual property portfolio in RNAi with 50 issued patents and over 250 pending applications worldwide. More information on Sirna Therapeutics is available on the Company’s web site at http://www.sirna.com .

Safe Harbor Statement

Statements in this press release which are not strictly historical are “forward-looking” statements which should be considered as subject to many risks and uncertainties. For example, most drug candidates do not become approved drugs. The development of Sirna-027 and Sirna-034 as well as Sirna’s other programs are still at a relatively early stage and subject to significant risks and unknowns. Moreover, Sirna’s ability to develop products and operate as a going concern requires significant cash to fund its operating programs. Additional risks and uncertainties include Sirna’s early stage of development and short operating history, Sirna’s history and expectation of losses and need to raise capital, the rate at which Sirna uses cash, the timing of receipt of development milestone payments from collaborating partners, Sirna’s need to obtain clinical validation and regulatory approval for products, Sirna’s need to obtain and protect intellectual property, risk of third-party patent infringement claims, Sirna’s need to attract and retain qualified personnel, Sirna’s need to engage collaborators, availability of materials for product manufacturing, the highly competitive nature of the pharmaceutical market, the limited trading volume and history of volatility of Sirna’s common stock, Sirna’s concentration of stock ownership, and risks from relocating Sirna headquarters. These and additional risk factors are identified in Sirna’s Securities and Exchange Commission filings, including the Forms 10-K and 10-Q and in other SEC filings. Sirna undertakes no obligation to revise or update any forward-looking statements in order to reflect events or circumstances that may arise after the date of this release.

Contacts: Rebecca Galler Robison Senior Director, Corporate Strategy Sirna Therapeutics, Inc. 303-449-6500 Francesca DeMartino The Ruth Group (646) 536-7024 fdemartino@theruthgroup.com

Sirna Therapeutics, Inc.

CONTACT: Rebecca Galler Robison, Senior Director, Corporate Strategy ofSirna Therapeutics, Inc., +1-303-449-6500; or Francesca DeMartino of TheRuth Group, +1-646-536-7024, fdemartino@theruthgroup.com, for SirnaTherapeutics, Inc.

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