We report on 25 patients who developed carcinoma of the prostate following suprapubic prostatectomy for benign hyperplasia. The average age at the time of surgery was 67.3 years. An average of 8.3 years (1-23 years) elapsed before detection of carcinoma. 12 of 25 patients were operated on at the Department of Urology, University of Vienna, between 1962 and 1986. At the same time, 972 patients underwent suprapubic prostatectomy. In our patients the incidence of carcinoma of the prostate following suprapubic prostatectomy amounts thus to at least 1.2% (12 of 972). In Austria, the incidence of carcinoma of the prostate in the comparable age group (70-79 years) is 0.34% per annum. This means that in an average observation period of 6.4 years (i.e. the average time before detection of carcinoma in 12 of 972 patients), almost 2.2% of the male population in Austria are affected by carcinoma of the prostate. Probably, part of the patients who underwent prostatectomy at our department turned to other departments of urology as soon as the complaints reappeared. Hence we may conclude that the incidence of carcinoma of the prostate following prostatectomy is almost identical with the incidence of carcinoma in a non-operated group. To determine the incidence of carcinoma of the prostate following suprapubic prostatectomy, 276 patients were called in again. Of these, 98 underwent follow-up examinations; no carcinoma of the prostate was detected. Since the biologic activity of the carcinoma after open prostatectomy is similar to that of nonoperated carcinoma, urologic follow-up examinations must be carried out regularly both in patients who underwent adenomectomy and in those who were not operated.