PURPOSE:This study investigated the functional significance of perineal complications after ileal pouch‐anal anastomosis.METHODS:Review of a prospective registry of 628 patients was undertaken. Bowel function was assessed by detailed functional questionnaire. Statistical analyses were performed using chi‐squared and Fisher's exact probability tests.RESULTS:Of 628 patients, 153 (24.4 percent) had 171 perineal complications. The 277 control patients had no complications. Complications included 66 (10.5 percent) anastomotic strictures, 28 (4.5 percent) anastomotic separations, 36 (5.7 percent) pouch fistulas, 41 (6.5 percent) episodes of pelvic sepsis, and 18 (2.9 percent) patients with multiple complications. After these complications were addressed, the pouch failure rate was low (10 percent); in 90 percent of patients, the pouch could be salvaged. Most pouch failures were the result of pouch fistulas, and most occurred in patients ultimately diagnosed with Crohn's disease. Functional results after cure of these perineal complications revealed no significant functional differences between control patients and those cured of anastomotic separations, anastomotic strictures, and pouch fistulas. Only a few minor differences were demonstrated in function after an episode of pelvic sepsis. The major deterioration in function occurred after treatment for multiple perineal complications.CONCLUSIONS:An appreciable number of perineal complications occur after ileal pouch‐anal anastomosis. Pouch‐perineal fistulas are associated with the highest pouch failure rate. The majority of these fistulas occur in patients ultimately diagnosed with Crohn's disease or indeterminate colitis. Although there is no substitute for good technique and sound clinical judgment in the success of ileal pouch‐anal anastomosis, if perineal complications are successfully treated, functional outcome is equivalent to that in patients without perineal complications.