Prostate cancer is a frequent cancer in old men which increases with age and is associated with wide geographical variation. Even if age-specific incidence rates remain stable, the problem of prostate cancer seems certain to increase in absolute terms simply because of the ageing of the population. This will have major economic implications for the future, particularly in Westernised societies, with any temporal trend in risk serving only to further compound the problem. However, since the risk of dying from prostate cancer has remained unchanged in many countries throughout this century, it may be that the increased incidence may be the result of increasing transurethral resection of the prostate procedures or screening techniques which have increased the detection and reporting of prostate cancer.