The aim of this work was to study the effects of previous subtotal colectomy (STC) with ileostomy and sigmoidostomy on the outcome of ileal J-pouch-anal anastomosis (IPAA) in patients with acute ulcerative colitis. Between 1983 and 1991, we conducted a prospective, nonrandomized study of 156 patients who underwent IPAA in our center. Fifty-five patients (34.3 percent) had undergone STC with ileostomy and sigmoidostomy for either severe acute colitis (36.5 percent of cases) or nonresolving acute colitis (63.5 percent) up to six months before IPAA with covering ileostomy. There were no perioperative deaths; six patients (11 percent) developed complications requiring reoperation (three cases of pelvic sepsis, two occlusions, and one stenosis of the ileostomy). IPAA was successfully carried out at a later stage in all cases. The results of IPAA in these patients were compared with those in 78 patients who underwent the classical two-stage IPAA procedure. The rates of pelvic sepsis and postoperative occlusion were lower in the subgroup of patients who underwent the three-step procedure. Three months after closure of the ileostomy, the mean number of daily stools was significantly lower in the patients who had undergone prior STC (5.09 vs. 5.9), but there was no significant difference between the two groups with regard to diurnal and nocturnal continence, the need to wear a pad, discrimination between gas and stools, or the use of antidiarrheal medication. In addition, there was no significant difference at one year in terms of functional parameters. We conclude that STC is a simple and safe procedure for the treatment of a severe attack of colitis and that it does not compromise the results of later IPAA. Because it does not increase the morbidity of subsequent IPAA and is associated with more rapid functional recovery, STC appears to be suitable for the treatment of patients with nonresolving acute colitis before the onset of malnutrition or steroid dependency.