[en] Background and aims: Infliximab (IFX) has been shown efficacious for moderate-to-severe ulcerative colitis (UC), but data on long-term efficacy are tacking. We investigated long-term outcome including colectomy rates in outpatients treated with IFX for refractory UC in a single referral centre, and evaluated if predictors could be identified. Methods: The first 121 outpatients (median age 38.0 years) with refractory UC treated with IFX were included. The primary outcome was colectomy-free survival. Secondary measures were sustained clinical response and serious adverse events. Results: From the 81 patients (67%) with an initial clinical response to IFX, 68% had a sustained clinical response. No independent predictors of sustained clinical response could be identified. Over a median (IQR) follow-up period of 33.0 (17.0-49.8) months, 21 patients (17%) came to colectomy. Independent predictors of colectomy were absence of short-term clinical response [Hazard ratio 10.8 (95% Cl 3.5-32.8), p < 0.001], a baseline CRP level >= 5 mg/L [Hazard ratio 14.5 (95% Cl 2.0-108.6), p=0.006] and previous IV treatment with corticosteroids and/or cyctosporine [Hazard ratio 2.4 (95% Cl 1.1-5.9), p=0.033]. Six patients developed a serious infection, three a malignancy, two a post-operative complication and one patient died (suicide). Conclusions: With a median follow-upof 33.0 months after start of IFX, 17% of patients with refractory UC needed colectomy, while sustained clinical response was present in 68% of initial responders. (c) 2008 European Crohn's and Colitis Organisation. Published by Elsevier B.V. All rights reserved.