OBJECTIVE The role of infliximab in treating pediatric ulcerative colitis (UC) is not defined. The authors previously have described their experience with the open label use of infliximab in nine children with moderate to severe UC. The aim of this study was to describe the outcome of these patients after a minimum 2-year follow-up and to describe the responses of eight additional patients to this medication. METHODS The authors reviewed all pediatric patients with UC who received infliximab at The Children's Hospital of Philadelphia from its first use until February 2003. Tolerance of the infusions and adverse events were recorded. RESULTS Follow-up information for a minimum of 2 years was reviewed for the nine initial patients. A total of 73 infliximab infusions were administered to these patients. Seven of nine (78%) patients were considered to be responders to the initial dose of infliximab. Two of these patients became nonresponders within 9 months of the first dose of infliximab and underwent colectomy. Of the remaining five (56%) patients with sustained response, two continue to receive infliximab infusions and three are doing well without infliximab. One patient experienced an infusion reaction, and one experienced herpes zoster infection. We have treated eight additional UC patients with infliximab. Seven (88%) patients were considered responders. One responder experienced relapse within 2 months. Overall, a short-term improvement was seen in 14 of 17 (82%) patients, and sustained improvement in 10 of 16 (63%) patients followed up for more than 9 months. All five patients with severe or fulminant UC, unresponsive to 2 weeks of intravenous corticosteroid therapy, experienced improvement with infliximab. Infliximab was well tolerated. CONCLUSIONS Infliximab is associated with short- and long-term clinical improvement in children and adolescents with moderate to severe UC.