In summary, the hormonal hypothesis remains one of the most important hypotheses in prostate cancer etiology. Although epidemiologic data regarding the role of hormones are still inconclusive, there are many intriguing leads. Armed with more complete methodological data, state-of-the-art hormone assays, sound epidemiologic design, and a more thorough analytical approach, a new generation of studies should yield critical data and insights to help clarify further the role of hormones in prostate cancer. These new studies may determine ultimately whether racial/ethnic differences in hormonal levels and in genetic susceptibility to hormone-metabolizing genes can help explain the very large racial/ethnic differences in prostate cancer risk.