A new BLSA study of Prostate Growth and Disease was begun in February 1993 to examine anatomic and physiologic correlates of normal prostate growth and the development and progression of benign prostatic hyperplasia (BPH) and prostate cancer. In the past year, three studies have been completed. The first BLSA study developed age-specific reference ranges for prostate-specific antigen velocity (rate of change) and compared the sensitivity and specificity of different prostate-specific antigen (PSA) criteria for the detection of prostate cancer. In order to determine the optimal PSA testing regimen, the second study examined the variability in PSA levels in men with BPH and prostate cancer when measured at different time intervals. This study showed that PSA measurements obtained at 3 month or 6 month intervals are unlikely to be clinically useful. The third study developed age-specific norms for serum androgen levels in men (see Project Z01 AG 0013-20 LCP). These norms will be used to examine the relationship between age-adjusted androgen levels and risk of BPH or prostate cancer.