DESCRIPTION (Taken from the applicant's Abstract) Chronic non-bacterial prostatitis is perhaps the most common diagnosis of men in the United States who seek the care of a urologist, yet almost nothing is known about the etiology of the disease or how to treat it effectively. Patients with this condition have a chronic, relapsing and episodic condition characterized by pain in the pelvic region, irritative and obstructive voiding symptoms, and difficulties with sexual function, including painful ejaculation. These symptoms are indistinguishable from those of men with infection of the prostate gland, and an infectious etiology for chronic non-bacterial prostatitis has dominated the thinking about this disease for many years. However, a large body of evidence accumulated over may years has failed to convincingly demonstrate that any infectious agent is responsible for symptoms in a significant proportion of men with the disease. Men diagnosed with the condition are typically treated with multiple courses of antibiotics for prolonged periods of time at great cost and with little proven benefit. The further definition of the disease will depend upon three steps. First, we must be able to objectively define who has the disease and how severe it is, based upon standardized criteria, including symptom scores and measurable parameters in patients. Second, we must search for differences between men who have the disease and normal men who do not, in order to gather objective information of potential etiologic significance. Such studies should include measures of infectious, inflammatory, immunologic, genetic and biochemical parameters for which we will search for statistically significant differences between men with disease and control men. Finally, therapies directed at identified causative factors as well as empirical therapies can be designed and objectively evaluated. We propose to contribute to this effort by serving as a clinical center for the design and performance of such studies in a multi-center setting. We will show that we have already made and are continuing to make a substantial effort to develop new insights into this disease, that we have significant expertise in immunologic and urologic research, and that we have a track record of patient recruitment into research studies in chronic non-bacterial prostatitis.