BACKGROUND/AIMS Many studies on infliximab have confirmed its efficacy in the remission induction and even maintenance in refractory and fistulizing Crohn's disease. We report the treatment efficacy of infliximab in Crohn's disease and ulcerative colitis refractory to steroid treatment and the complications of infliximab treatment. METHODS We performed infliximab administration in 5 cases (3 Crohn's disease, 2 ulcerative colitis) refractory to systemic steroid treatment and 5 cases of Crohn's disease with fistula. Patients received an intravenous infusion of infliximab at 3-5 mg/kg body weight. RESULTS In 3 cases of refractory Crohn's patients, clinical response and remission induction were obtained in 2 (67%) and 1 cases (33%). After infusion of infliximab, the occlusion of internal fistula could be found in all 2 cases. Two out of 3 cases of anal fistula were completely healed. In two cases of refractory ulcerative colitis, one case who showed clinical manifestation of toxic megacolon had improved and avoided the colectomy, but the other case did not respond to the infusion of infliximab and underwent colon resection. CONCLUSIONS We found that administration of infliximab is an effective alternative for refractory and fistulizing Crohn's disease but further studies are necessary for refractory ulcerative colitis.