BACKGROUND: Severe ulcerative colitis is a life-threatening disorder, despite i.v. glucocorticoids treatment. Infliximab has been proposed as a safe rescue therapy. AIM: To evaluate short- and long-term effectiveness and safety of infliximab in severe refractory ulcerative colitis. METHODS: Eighty-three patients with severe ulcerative colitis (i.v. glucocorticoids treatment-refractory) were treated with infliximab in 10 Italian Gastroenterology Units. Patients underwent one or more infusions according to the choice of treating physicians. Short-term outcome was colectomy/death 2 months after the first infusion. Long-term outcome was survival free from colectomy. Safety data were recorded. RESULTS: Twelve patients (15%) underwent colectomy within 2 months. One died of Legionella pneumophila infection 12 days after infliximab. Early colectomy rates were higher in patients receiving one infusion (9/26), compared with those receiving two/more infusions (3/57, P = 0.001, OR = 9.53). Seventy patients who survived colectomy and did not experience any fatal complications were followed-up for a median time of 23 months; 58 patients avoided colectomy during the follow-up. Forty-two patients were maintained on immunosuppressive drugs. No clinical features were associated with outcomes. CONCLUSIONS: Infliximab is an effective and relatively safe therapy to avoid colectomy and maintain long-term remission for patients with severe refractory ulcerative colitis. In the short term, two or more infusions seem to be more effective than one single infusion.