Fourteen patients with ulcerative colitis underwent formation of an S ileal pouch and construction of a stapled pouch-anal anastomosis by a modified technique, which eliminated the use of purse-string sutures. Eleven have had their covering ileostomies closed. Anal manometry performed before and a median of 9 months after ileostomy closure showed significant impairment of internal anal sphincter function. Night evacuation was significantly reduced in the stapled group compared with a similar group of patients who had undergone S ileal pouch formation, mucosal proctectomy and manual transanal anastomosis, but this was the only parameter of function to show a difference. A stapled pouch-anal anastomosis may be superior to the conventional procedure but it still may lead to internal anal sphincter damage which cannot be due to mucosectomy or prolonged anal retraction.