Statistic study was made on 685 outpatients with erectile dysfunction during 13 years periods from 1979 to 1991 in the Department of Urology, Takamatsu Red Cross Hospital. The age distribution showed the highest frequency in the thirties decade (27.9%). 1. Diagnosis Nocturnal penile tumescence monitoring was the only method to distinguish organic impotence from functional impotence during the first 5 years. From 1984 we have been able to diagnose corporal veno-occlusive insufficiency (CVI) by papaverine test and dynamic infusion cavernosometry and cavernosography. Measurement of penile brachial index and pelvic angiography were performed to diagnose arterial insufficiency (AI). In neurological examination we have measured bulbo-cavernosus reflex latency and nerve conduction velocity of the dorsal penile nerve and performed microvibration measurement and sweat spots test. All diagnostic methods were established in 1987 and we have been able to classify about 80% patients. We classified 305 patients during the last 5 years from 1987 as follows: psychogenic; 31.1%, CVI; 20.0%, AI; 7.9%, neurogenic; 7.9%, others; 14.1%, drop-out and unknown; 19.0%. 2. Treatment In the beginning only counseling and drug therapy were performed. However we lately performed various suitable methods for individuals based on their diagnoses. We performed counseling, drug therapy and intracavernous injection of vasoactive drug therapy for recovery of spontaneous erection (vascular training) for psychogenic IMP. The efficacy rate of counseling was low (30.4%) but that of drug therapy was 41.6%, and that of vascular training, 64.2%. For CVI without other factors we performed venous surgeries. Only about 25% of them perform sexual intercourse with or without self injection of vasoactive drug (self injection).(ABSTRACT TRUNCATED AT 250 WORDS)