The primary goal of this proposal is to determine if a 5-alpha reductase 'challenge' improves screening performance of PSA and DRE in men who are scheduled for prostate biopsy. Currently a higher PSA level leads to a recommendation for prostate biopsy, causing hundreds of thousands of unnecessary biopsies annually in the U.S. We will show that a three-month treatment with finasteride for men with high PSA levels will better predict the man who should have a prostate biopsy. PSA performance after finasteride 'challenge' will also be compared with new tests for prostate cancer. Finasteride is supplied by Merck and Company, Incorporated.