Rexahn Pharmaceuticals, Inc. (NYSE Amex: RNN), a clinical stage pharmaceutical company commercializing potential best in class oncology and CNS therapeutics, today announced that the United States Patent & Trademark Office has issued U.S. Patent No. 8,034,829 to Rexahn, entitled “5, 6, or 7-Substituted-3-(hetero) arylisoquinolinamine derivatives and therapeutic use thereof.” This patent covers several new isoquinolinamine compounds and their pharmaceutical composition and method for producing an anti-tumor effect. The patent specifically covers Rexahn’s compound RX-8243, currently in pre-clinical development. In a recently published study in Bioorganic & Medicinal Chemistry Letters [ 20:5277-5281, 2010], RX-8243 exhibited potent anti-tumor properties in several cancer cell lines, as well as in paclitaxel-resistant human colorectal xenograft models. RX-8243 also demonstrated a synergistic cytotoxic effect when combined with several known cancer drugs against human cancer cells. Rick Soni, President of Rexahn, commented, “This new US patent for arylisoquinolinamine compounds is an important step in the development of RX-8243 and further strengthens our global intellectual property position around our oncology pipeline.” About Rexahn Pharmaceuticals, Inc. Rexahn Pharmaceuticals, Inc. is a clinical stage pharmaceutical company dedicated to developing and commercializing first in class and market leading therapeutics for cancer, CNS disorders, sexual dysfunction and other unmet medical needs. Rexahn currently has three drug candidates in Phase II clinical trials, Archexin®, Serdaxin®, and Zoraxel™ – all potential best in class therapeutics – and a robust pipeline of preclinical compounds to treat multiple cancers and CNS disorders. Rexahn also operates key R&D programs of nano-medicines, 3D-GOLD, and TIMES drug discovery platforms. For more information about Rexahn, please visit www.rexahn.com. Safe Harbor To the extent any statements made in this press release deal with information that is not historical, these are forward-looking statements under the Private Securities Litigation Reform Act of 1995. Such statements include, but are not limited to, statements about Rexahn’s plans, objectives, expectations and intentions with respect to future operations and products and other statements identified by words such as “will,” “potential,” “could,” “can,” “believe,” “intends,” “continue,” “plans,” “expects,” “anticipates,” “estimates,” “may,” other words of similar meaning or the use of future dates. Forward-looking statements by their nature address matters that are, to different degrees, uncertain. Uncertainties and risks may cause Rexahn’s actual results to be materially different than those expressed in or implied by Rexahn’s forward-looking statements. For Rexahn, particular uncertainties and risks include, among others, the difficulty of developing pharmaceutical products, obtaining regulatory and other approvals and achieving market acceptance; the marketing success of Rexahn’s licensees or sublicensees; the success of clinical testing; and Rexahn’s need for and ability to obtain additional financing. More detailed information on these and additional factors that could affect Rexahn’s actual results are described in Rexahn’s filings with the U.S. Securities and Exchange Commission, including its most recent annual report on Form 10-K and subsequent quarterly reports on Form 10-Q. All forward-looking statements in this press release speak only as of the date of this press release. Rexahn undertakes no obligation to update or revise any forward-looking statement, whether as a result of new information, future events or otherwise.