In 2005, more than 200,000 new cases of prostate cancer will be detected in the United States, and about 30,000 men will die from the disease. African American men are particularly hard-hit, dying from this disease at more than twice the rate of European Americans. The reasons for this racial/ethnic disparity are largely unknown, but probably involve an interaction among genetic, environmental, and social factors. This Issue Brief reviews current knowledge about the genetic basis of prostate cancer and summarizes ongoing research at Penn that investigates the role of genetics in prostate cancer treatment and outcomes.