Chronic ulcerative colitis was treated by elective colectomy in 158 patients. Proctocolectomy and ileostomy was performed in 140 patients and colectomy and ileorectal anastomosis (CIRA) in 18 patients. The operative mortality was 2.5%, and postoperative complications, mostly infections, occurred in 38%. Within a 2-year postoperative period another 1.9% of the patients died, and late complications occurred in 18%. Colorectal carcinoma was present at the time of colectomy in 5.1% and developed some years later in another two patients primarily operated on with CIRA. Half of the cancer patients died of malignancy. Most extracolic complications, present in 25% of patients before colectomy, regressed or disappeared after operation. Half of the patients operated on with CIRA needed to have their rectum removed within a few years because of cancer or proctitis, and few of the rest had lasting relief of symptoms.