SummaryAs the digital diagnosis of carcinoma of the prostate is open to a significant error, oestrogen therapy or radical surgery should not be begun on this evidence alone. Some confirmatory evidence should be obtained.Trocar perineal biopsy is a useful method of confirming the diagnosis in:(a) Cases in within carcinoma is suspected clinically.(b) Hard nodules in the prostate.(c) Cases with extensive osteosclerotic lesions in which the prostate is not unduly hard.The Veenema trocar gives a simple and effective method of performing this with a good degree of accuracy and a minimum of complications.