The effectiveness of intracavernous PGE1 injections for spontaneous erections has been assessed in this study. Patients with disorders of erection were treated with 6 intracavernous PGE1 injections (10 to 25 micrograms) at 15-day intervals. An exploration was undertaken in these patients to establish the cause of the disorders of erection. Spontaneous erections were compared before and after the six PGE1 injections. Thirty-five patients were studied. Their average age was 58.8 years. The cause of the disorders of erection was organic [22] or psychogenic [13]. Thirty-one patients (88%) had an erection allowing sexual intercourse after the first PGE1 injection, two had a weak erection and two had no erection. After more than one year, 24 (73%) of the 33 patients treated reported improvement of spontaneous erections, allowing intercourse; 11 (33%) occasionally received a PGE1 injection. Nine (27%) were not improved, including two psychogenic cases. The number of patients who occasionally resorted to PGE1 injections raised from 6 to 11 (33%). This study shows the effectiveness--at least temporarily--of repeated PGE1 on spontaneous erections, owing to an action on the psychogenic component of disorders of erection, but maybe also to a local, long-lasting action of PGE1 on the cavernous tissue.