One hundred thirteen patients with either chronic ulcerative colitis (108 patients) or familial polyposis coli (five patients) received an ileal J pouch-anal anastomosis after sphincter-saving proctocolectomy. There were no postoperative deaths. Leaks (radiologic and/or clinical) from the pouch or ileoanal anastomosis occurred in 14 per cent of patients. Small-bowel obstruction, requiring operative correction, occurred in 7 per cent and 3 per cent, respectively, of patients after either proctocolectomy or closure of the loop ileostomy. All 66 patients whose diverting ileostomy had been closed for at least three months could defecate spontaneously and their mean (+/- SE) stool frequency per 24 hours was 9.0 +/- 1 at one month and 5.9 +/- at 12 months. Major fecal incontinence was observed in 3 per cent of patients, and two patients eventually required a permanent ileostomy. The ileal J pouch-anal anastomosis has become our procedure of choice in selected patients who require proctocolectomy.