Prostate cancer is a leading cause of morbidity and mortality in men and has significant treatment-associated complications. Prostate cancer chemoprevention has the potential to decrease the morbidity and mortality associated with this disease. Chemoprevention research to date has primarily focused on nutrients and 5 alpha-reductase inhibitors (5ARIs). A large randomized trial (SELECT) found no favorable effect of selenium or vitamin E on prostate cancer prevention. Two large randomized placebo controlled trials (the PCPT and REDUCE trials) have been published and have supported the role of 5ARIs in prostate cancer chemoprevention; however, these trials also have prompted concerns regarding the increase in high-grade disease seen with treatment and have not been approved by the US Food and Drug Administration (FDA) for chemoprevention. Conclusive evidence for the chemopreventive benefit of nutrients or vitamins is lacking, whereas the future role of 5ARIs remains to be clarified.