The aim of this study was to evaluate the physiological and manometric changes of anorectal function after proctocolectomy and ileal J pouch anastomosis performed in 13 patients. A short muscular rectal cuff was conserved in the first 5 patients, mucosectomy was performed in the next patients (Group M), and the entire rectum and proximal portion of the anal canal (1 mm above the dentate line) were resected without mucosectomy (Group WM) in the most recent patients. With a median postoperative follow-up of 18 months, anorectal continence was perfect in 9 patients, and minimal incontinence were observed in 4 patients (2 patients in Group M, and 2 patients in Group SM). In Group M, the resting lower anal canal pressure was significantly decreased after the operation and was less than the postoperative resting lower anal canal pressure observed in Group SM. The resting upper anal canal pressure in continent patients was inferior to the postoperative values measured in patients with minimal incontinence. In all the groups, no change in squeeze pressure was observed after the operation. During the postoperative period, the rectoanal inhibitory reflex was absence in all patients. The volume necessary for sensation threshold was increased after the operation, in the same number of patients in Group M and SM, and more frequently in continent patients compared with patients with soiling. The absence of muscular rectal cuff and mucosectomy seems to provide best results than rectal cuff preservation. After the operation, a marked decrease in the resting pressure and an increase in the volume necessary to onset of threshold sensation, were associated with the presence of minimal incontinence.