The authors report about the catamnestic inquiry concerning 13 patients with sexual problems treated with cyproterone acetate (CA) of whom 12 relapsed repeatedly in sexual delinquency. Since 1972 the Basle University Psychiatry Outpatient-Department treated 12 of these patients with CA-tablets and psychotherapy. One patient was treated in the same way by a head physician of the Basle University Psychiatry Hospital. Reason for CA-intake: 6 patients took CA because they were obliged by legal order. 4 patients were "voluntarily" ready to take CA for fear of imprisonment. 2 patients who were not accountable for their crimes were treated with CA and one patient desired CA-medication because he suffered from his masochism severely. The mean age of the patients was 34.5 years, the mean daily dosage 115 mg. Result of CA-therapy and psychotherapy: 11 patients (85%) did not relapse under CA treatment which lasted on the average three years. 3 patients succeeded under CA treatment with full social integration. 3 patients showed an improvement of social integration and 3 patients one of whom received Disulfirame (Antabus) reduced alcohol intake. After having ended or interrupted CA-medication two of 7 patients relapsed. 3 patients who did not relapse after stopping the CA-intake were observed for as long as 3 years. As forensic psychiatric consequence it follows that CA in combination with psychotherapy can be considered--in spite of the side-effects linked with it--as a method of choice in the ambulatory treatment of sexual delinquents who have frequently relapsed and whom psychotherapy alone did not help.