Stool frequency after ileal pouch-anal anastomosis (IPAA) is about 5/day after adaptation during the first year. It depends on stool volume and pouch capacity, not on the design of the pouch. In most cases evacuation is spontaneous and as complete as in healthy rectum. 67% of patients are perfectly continent, while 19% have to wear pads due to intermittent leakage. Complete incontinence is reported in 0-4% of the patients. Preservation of the anal transitional zone by the double-stapling technique does not improve functional results when compared to endoanal mucosectomy or intersphincteric resection. Impairment of continence is caused by damage of the internal sphincter with consecutive decrease of the pouch-anal pressure gradient. Despite altered reflex activity, stool discrimination is preserved in most patients. The loss of colonic water and electrolyte absorption is compensated by decreased renal excretion. Alterations in bile acid metabolism are lower after IPAA than after ileostomy. Bacterial overgrowth may lead to deterioration of the functional results.