Conventional treatment options for patients with severe corticosteroid-refractory ulcerative colitis (UC) include intravenous cyclosporine, which is frequently limited by toxicity, or colectomy. The efficacy of infliximab was investigated in the treatment of 16 patients with severely active UC refractory to conventional therapy; 7 of these patients were considered for colectomy pending medical failure. All patients received a single infusion of infliximab, 5 mg/kg; 6 of 16 patients (38%) received a second infusion approximately 5 months later. Efficacy was assessed by clinical response (defined as the lack of symptoms) as well as endoscopic and histologic outcomes. Clinical, endoscopic, and histologic improvement was observed in 14 of 16 patients (88%) after treatment with infliximab. Surgery was avoided in six of seven surgical candidates (86%). Clinical remission was maintained in 14 of 16 patients (88%) for > or = 4 months, and 4 of 16 patients (25%) for 7-10 months. Most of the treated patients were completely withdrawn from corticosteroid therapy. Treatment with infliximab induced endoscopic remission at 30 days and a significant improvement from baseline in mean histologic score (p < 0.001). In conclusion, infliximab improved clinical, endoscopic, and histologic outcomes in patients with severely active UC refractory to conventional therapy, allowing corticosteroid sparing and reducing the need for colectomy.