Conventional treatment options for patients with severe steroid-refractory ulcerative colitis (UC) include intravenous cyclosporine, which is frequently burdened by toxicity, or colectomy. Preliminary data suggest a benefit of anti-tumor necrosis factor alpha (Infliximab) therapy in patients with steroid refractory UC. Thirteen patients with severe UC, refractory to therapy with methyl-prednisolone, 60 mg IV daily were treated with a single intravenous infusion of Infliximab 5 mg/kg. Ten out of 13 patients (77%) had a clinical response to therapy defined by a CAI < or = 10 on two consecutive days. Two patients (15%) underwent total colectomy because of clinical worsening; one patient refused surgery and was lost to follow-up. Infusion with Infliximab produced no significant adverse events. The mean time of follow-up was 25.6 months (range 17-24); in this period of time 8 out of 10 patients (80%) maintained clinical remission and were able to discontinue corticosteroids therapy. Infliximab appears to be an effective agent for inducing long standing remission in refractory patients with severe UC.