Prostaglandin E1 (PGE1) is currently the vasoactive drug of choice for intracavernous self-injection therapy in the treatment of erectile dysfunction. PGE1 is often said to have a low incidence of side-effects. However, real long-term follow-up reports are rare. Here, a report is presented on 32 patients who joined a long-term self-injection programme in which they used PGE1 for a minimum of 5 years under standardized protocol conditions. All these patients had an organic aetiology of erectile dysfunction, and their mean age was 58.7 +/- 8.6 years. The period of observation was on average 75.4 +/- 16.9 months, and the PGE1 dosage 13.5 +/- 5.9 micrograms. A total of 6799 injections were registered. The average number of injections was 213 +/- 127 per patient, which is 2.8 injections per month and patient. As regards side-effects, haematomas were registered in 1.9% of the patients and five cases of prolonged erection (0.07%) caused by unauthorized redosing were noted. Three patients developed reversible penile nodules. In 10 patients, the initial dosage had to be increased. Five patients dropped out after 5 years, none of them due to treatment complications. It is concluded that PGE1 self-injection therapy is a simple and reliable method for long-term use with hardly any side-effects. The patients do not stop treatment because of complications.