Chemoprevention trials for several malignancies are completed, planned, or underway. Prostate cancer is one of the most common forms of cancer and understandably has received considerable recent attention as a potential target for chemoprevention. This article examines chemoprevention trials for prostate cancer, including the Prostate Cancer Prevention Trial, Selenium and Vitamin E Cancer Prevention Trial, and cyclooxygenase inhibitors in the prevention of prostate cancer.