Iloprost is useful in the short-term treatment of severe Raynaud's phenomenon and ischaemic ulcers in patients with systemic sclerosis (SSc), but its long-term effects are largely unknown. The aim of this study was to report long-term outcome (median follow-up 36 months) in a prospective observational study of a cohort of 30 consecutive patients with SSc who received iloprost therapy with maintenance infusions every 3 weeks after an initial cycle of 5 consecutive days. At the end of the observation, compared to the pretreatment point, we observed complete healing of digital ulcers in 19/21 patients (90%), a decrease of the Raynaud's phenomenon visual analogue score from 10/10 (25th-75th percentile 7-10) to 5/10 (4-6.75) ( P <0.001) and, in patients with diffuse cutaneous involvement, of the modified Rodnan skin thickness score from 25.5 (16.5-31.5) to 16 (13.5-20) ( P = 0.02), minimal improvement of the Health Assessment Questionnaire from 0.87 (0.68-1.37) to 0.75 (0.62-1.25), which was neither statistically nor clinically significant. The forced vital capacity was not significantly changed, but the diffusion capacity corrected for the alveolar volume decreased from 71% (54-76.7) of the expected value to 62% (51.5-71) ( P = 0.02). In one patient with limited SSc a positive effect on pulmonary hypertension was observed. Six patients, after a median of 25 months of treatment and healing of digital ulcers, discontinued the therapy; after a median of 10 months ulcers did not recur in five of these six. Other reasons for discontinuation were: tolerability (1), disease progression (normotensive renal crisis: 1), and death due to intracranial haemorrhage (1). This same patient had previously suffered a central retinal vein thrombosis. In conclusion, long-term therapy with iloprost in patients with SSc has a durable effectiveness on ischaemic ulcers and Raynaud's phenomenon, but it is not possible to conclude that the natural history of the disease was modified.