Restorative proctocolectomy is now the treatment of choice for most patients with ulcerative colitis and familial polyposis coli. Temporary defunctioning ileostomy has been advocated during the period of anastomotic healing to prevent pelvic sepsis. However, the ileostomy itself may be a source of significant complications. To examine ileostomy function we reviewed thirty five patients (mean age 34.5 +/- 1.95 years) who underwent restorative proctocolectomy. Thirty four patients had a defunctioning ileostomy established at the time of pouch anal anastomosis. Closure of the ileostomy has been carried out in 33 patients (mean closure time 3.1 +/- 0.29 months). One patient underwent early pouch excision. Thirteen of the 35 patients developed post-operative complications (37%), two directly related to the defunctioning ileostomy. Both occurred following closure of the stoma and required laparotomy. Serious complications associated with defunctioning ileostomy as demonstrated in this study are uncommon (8.5%). Given the potentially disastrous consequences of a pouch-anal anastomotic leak we feel that the relatively low morbidity associated with a defunctioning ileostomy justifies its continued routine usage in the operation of restorative proctocolectomy.