PURPOSE: Colonic pouches have been used to improve the reservoir function of the neorectrum after a ultra-low anterior resection for treatment of rectal cancer. The purpose of this study was to compare the safety and the functional outcome between a straight anastomosis, an anastomosis using coloplasty, and that using a colonic J-pouch in patients who had undergone an ultralow anterior resection. METHODS: From 2004 through 2006, 60 patients underwent a coloanal straight (straight group: n=23), coloplasty (coloplasty group: n=19), or colonic J-pouch (J-pouch group: n=18) anastomosis to the anal canal after a total mesorectal excision of the rectal cancer. We retrospectively reviewed the medical records of those patients for clinical outcomes according to the reservoir type. The median follow-up interval was 23.7 (4.4-40.9) mo. RESULTS: The anastomotic leakage rate was higher in the coloplasty group (21.1%) than in the straight group (8.7%) or in the J-pouch group (0%), but the difference was not significant (P=0.1). The mean number of bowel movements per day was significantly lower in the coloplasty group (3.6) and in the pouch group (3.1) than in the straight group (6.2) (P=0.015). No statistically significant differences were found among the three groups regarding other functional outcomes, including use of antidiarrheal drugs (P=0.971), gas incontinence (P=0.256), fecal incontinence (P=0.544), use of pads (P=0.782), difficulty of evacuation (P=0.496), and use of enemas (P=0.712). CONCLUSION: Reconstruction with a coloplasty or a colonic J-pouch in patients undergoing a low colorectal or coloanal anastomosis after rectal cancer surgery seems to decrease the number of daily bowel movements compared to a straight anastomosis. However, the anastomotic leakage rate of coloplasty group was higher than that of the straight-anastomosis group.