The clinical efficacy of the prostacyclin analogue iloprost was studied during a 2 week treatment and 6 month follow-up period in 103 patients with ischaemic ulcers who were randomised to receive active treatment or placebo. Responders were defined as those patients who achieved healing of at least one third of the ulcer area during the study period. The overall responder rate was 41.3%, compared with 25% for the control group (P = 0.086). Side effects including flushing and headache, were common. The study population had a mortality of 23% during the 6 month period, the amputation rate was 43.5% for iloprost and 50% for placebo treated patients. In this severely diseased population of patients a treatment period limited to 2 weeks did not sufficiently improve ulcer healing.