This study was designed to determine the influence of ileal pouch capacity and anal sphincteric function an the clinical outcome after ileal pouch-anal anastomasis. A total of 24 patients who had undergone ileal pouch-anal anastomosis (J pouch) for ulcerative colitis were studied. The 24-hour stool frequency was found to be inversely correlated with the sensitivity threshold volume (STV), maximal tolerance volume (MTV), and distensibility, hut was independent of the maximal resting pressure and maximal squeeze pressure, patients experiencing nocturnal fecal incontinence had maximal resting pressures that were significantly lower than those of nocturnally continent patients, Among the patients with fecal incontinence, those with frequent soiling had lower resting pressures, STV, and distensibility than the patients with intermittent spotting, in addition, the STV in patients needing nocturnal evacuation were lower than those of patients who did not evacuate after falling asleep, The conclusions are as follows, Both stool frequency and the need for nocturnal pouch evacuation correlated directly with pouch volume. Anal incontinence was more common in patients with Bow internal sphincteric function, In addition, frequent and gross nocturnal incontinent patients demonstrate a worse function in both the anal sphincter and reservoir than those with intermittent spotting.