Molecular biologic studies have now identified a number of important genetic and epigenetic mechanisms that cause alterations in growth and differentiation genes in prostate cancer. In addition to DNA deletion and point mutation, DNA methylation represents a new paradigm for the inactivation of tumor suppressor or growth suppressor genes. The identification of new genes, including a prostate cancer susceptibility locus, may furnish further insight into the molecular characteristics of prostate cancer and permit the early identification of affected individuals.