A retrospective review was undertaken to determine factors important in predicting functional results following the ileal reservoir and ileoanal anastomosis procedure. One hundred seventy-nine patients underwent ileal reservoir and ileoanal anastomosis at the University of Toronto between December 1981 and January 1987. One hundred sixty-three patients had ulcerative colitis, 11 had familial adenomatous polyposis, and five had Crohn's disease. A J-reservoir was constructed in 72 patients and an S-reservoir in 107 patients. Functional results were assessed in 102 patients who had their loop ileostomies closed for more than one year. The most significant technical complications were anal anastomotic leaks (10 percent), reservoir anastomotic leaks (3.9 percent), anal anastomotic stricture (7.8 percent), late fistula-inano (2.8 percent), small-bowel obstruction (19 percent), and loop ileostomy complications (23 percent). Overweight males and patients with operative blood loss greater than 1000 cc developed anal stricture more frequently (P less than .005). Patients who had a stapled J-reservoir had a higher rate of reservoir leak. The average number of bowel movements reported by patients for 24 hours was 6.2 +/- 3.1. Only ten (9.8 percent) patients had to intubate their reservoir to empty it. Urgency was experienced by 24 patients and soilage at night by 23 (22.5 percent) and during the day by 18 (17.6 percent). Seven patients (6.8 percent) were incontinent during the night and only one during the day. Pouchitis was reported in 16 patients (15.7 percent). Patients with anal anastomotic stricture had more urgency and pouchitis, and had to intubate their reservoir more frequently (P less than .05). No other factors analyzed affected technical or functional results.