PURPOSE: Functional disturbances are common after anterior resection for rectal cancer. This study was designed to compare functional and physiologic outcome after low anterior resection and total mesorectal excision with a colonic J-pouch or a sideto-end anastomosis. METHODS: Functional and physiologic variables were analyzed in patients randomized to a J-pouch (n = 36) or side-to-end anastomosis (n = 35). Postoperative functional outcome was investigated with questionnaires. Anorectal manometry was performed preoperatively and at six months, one year, and two years postoperatively. RESULTS: There was no statistical difference in functional outcome between groups at two years. Maximum neorectal volume increased in both groups but was approximately 40 percent greater at two years in pouches compared with the side-to-end anastomosis. Anal sphincter pressures volumes were halved postoperatively and did not recover during follow-up of two years. Male gender, low anastomotic level, pelvic sepsis, and the postoperative decrease of sphincter pressures were independent factors for more incontinence symptoms. CONCLUSIONS: Colonic J-pouch and side-to-end anastomosis gives comparable functional results two years after low anterior resection. Neorectal volume had no detectable influence on function. There was a pronounced and sustained postoperative decrease in sphincter pressures. PURPOSE: Functional disturbances are common after anterior resection for rectal cancer. This study was designed to compare functional and physiologic outcomes after low anterior resection and total mesorectal excision with a colonic J-pouch or a sideto-end anastomosis. METHODS: Functional and physiologic variables were analyzed in patients randomized to a J-pouch (n = 36) or side-to-end anastomosis (n = 35). Postoperative functional outcome was investigated with questionnaires. Anorectal manometry was performed preoperatively and at six months, one year, and two years postoperatively. RESULTS: There was no statistical difference in functional outcome between groups at two years. Maximum neorectal volume increased in both groups but about 40 percent greater at two years in pouches compared with the side-to-end anastomosis. Anal sphincter rates volumes were halved postoperatively and did not recover during follow-up of two years. Male gender, low anastomotic level, pelvic Sepsis, and the postoperative decrease of sphincter pressures were independent factors for more incontinence symptoms. CONCLUSIONS: Colonic J-pouch and side-to-end anastomosis gives comparable functional results for two years after low anterior resection. Neorectal volume Had no detectable influence on function. There was a pronounced and sustained postoperative decrease in sphincter pressures.