Twenty-five patients with ulcerative colitis were treated between 1959 and 1986 at the Mount Sinai Hospital, with severe gastrointestinal hemorrhage as their major complaint. Twenty-two patients required operation, while three patients were treated medically. Total proctocolectomy with ileostomy was carried out in 5 patients, and subtotal colectomy accompanied by mucous fistula (14), Hartmann closure (2), or ileosigmoidostomy (1) was performed in 17 patients. Eleven of the patients who underwent operation had emergency colectomies, while the remaining 11 had semielective procedures. Subtotal colectomy was performed in 10 of the 11 emergency cases. Indications for emergency surgery were massive hemorrhage alone in seven patients and severe hemorrhage complicated by toxic megacolon in four patients. One patient died postoperatively of a perforated duodenal ulcer following emergency subtotal colectomy. There were two late deaths from leukemia in one surgically treated patient and one medically treated patient at 9 and 18 months, respectively. All 4 of the 25 patients with remaining intact rectums were alive and well at 3- to 12-year follow-up. Subtotal colectomy can be undertaken in patients with massive hemorrhage from ulcerative colitis for whom subsequent ileoanal anastomosis is planned, provided that one recognizes and is prepared for the approximately 12% risk of continued rectal hemorrhage.