BACKGROUND Acute major gastrointestinal hemorrhage is uncommon in inflammatory bowel disease. METHODS We characterized the clinical features and course of such hemorrhage in patients at our institution from 1989 to 1996. RESULTS Thirty-one patients had acute lower gastrointestinal bleeding from inflammatory bowel disease and one had upper gastrointestinal bleeding from duodenal Crohn's disease. Three patients had ulcerative colitis and 28 had Crohn's disease, representing 0.1% of admissions for ulcerative colitis and 1.2% for Crohn's disease. In addition, another patient bled from an ileal J-pouch. In patients with Crohn's disease, the site of bleeding was duodenal in 1, small intestinal in 9, ileocolonic in 8, and colonic in 10. All ulcerative colitis patients had pancolitis. Medical therapy was initiated in 27 patients, including endoscopic therapy in 3. Five patients underwent surgery immediately, and 7 medically treated patients eventually required surgery for ongoing or recurrent bleeding. CONCLUSIONS Acute major gastrointestinal bleeding is uncommon in inflammatory bowel disease. Most cases are due to Crohn's disease, without a predilection for site of involvement. The presence of an endoscopically treatable lesion is uncommon, and surgery is required in less than half of cases during the initial hospitalization. Recurrent hemorrhage is not rare, and for these cases surgery may be the most appropriate treatment.