Background: Previous research has shown that infliximab (IFX) is effective in the management of moderate to severe active ulcerative colitis (UC). Latin American studies are lacking. Aim: To evaluate the efficacy of IFX treatment (including corticosteroid withdrawal, complete mucosal healing, colectomy and hospitalization rates) in patients with moderate to severe UC. Methods: A retrospective and descriptive study was conducted on patients with UC in Medellín (Colombia). We included patients steroid dependent or refractory to conventional treatment. Results: Between October 2005 and July 2011, 28 patients with moderate to severe UC received IFX infusions; the median of the follow-up was 27.4 months (range: 1-69 months). Twenty-four patients (86%) had a short-term primary response, whilst 19 (68%) achieved initial clinical remission. After 1 year, 17 (71%) out of the 24 patients who had an initial response were also showing a sustained response, and 10 (42%) remained in clinical remission. At 6 months, complete mucosal healing was observed in 29% of patients and endoscopic improvement in 57%. Conclusions: This is the first study to evaluate the IFX use in patients with moderate to severe active UC in a Latin American population. We found that IFX therapy is effective for inducing clinical remission, and that most patients who had an initial response showed a long-term sustained response.