ARM II (Prostate Screening): Participants undergo blood sample collection for PSA analysis at baseline and annually for 5 years. Serum that is not used in the study will be stored in an NCI biorepository. Participants also undergo a DRE at baseline and annually for 3 years. A scheduling and tracking procedure is implemented to ensure regular attendance at repeat screens for participants screened negative or for those who are designated suspicious or positive at screening but for whom subsequent diagnostic procedures do not reveal prostate cancer (follow-up diagnostic procedures are through their own medical care environment). Participants diagnosed with prostate cancer via a screening test are referred for treatment in accordance with current accepted practice for appropriate stage of disease, patient age, and medical condition; a procedure is provided for contact with qualified medical personnel to insure appropriate therapy.