AIM: This study was designed to analyze the functional and clinical outcomes of straight coloanal anastomosis com pared with colonic J-pouch performed after low anterior resection. MATERIALS AND METHODS: Between September 1989 and June 1996, all patients who underwent low anterior resection with anastomosis less than 4 cm from the dentate line were classified into two groups based on the restoration of intestinal continuity: "straight" coloanal anastomosis (n = 39) or colonic J-pouch (n = 44). Both groups were assessed according to the level of anastomosis, anastomotic complications (stricture, leak, pelvic abscess), age, and gender. For comparison of functional outcome, daily bowel-movements, tenesmus, urgency, incontinence score (range, 0-20), and anorectal manometric findings were evaluated preoperatively and at six months, and one and two years after surgery. RESULTS: There were no significant differences between the groups relative to age: (coloanal anastomosis, 66.3 +/- 10.1 (range, 46-86), vs. colonic J-pouch, 64.9 +/- 13.2 (range, 39-88) years); gender (females): (coloanal anastomosis, 46.2 percent vs, colonic J-pouch; 38.6 percent); diagnosis: (rectal carcinoma: coloanal anastomosis, 84.6 percent, vs. colonic J-pouch, 77.3 percent); preoperative incontinence score (coloanal anastomosis, 1.5 +/- 4.6, vs colonic J-pouch, 1.1 +/- 4); bowel movements: (coloanal anastomosis, 2.1 +/- 2.3, vs, colonic J-pouch, 2.1 +/- 1.9/day); level of anastomosis: (coloanal anastomosis, 1.8 +/- 1.3, vs, colonic J-pouch, 1.5 +/- 1.3 cm from the dentate line); history of perioperative radiation therapy: (coloanal anastomosis, 15.4 percent, vs. colonic J-pouch, 20.5 percent); or manometric findings. There was also no significant difference in postoperative mortality: (coloanal anastomosis, 5.1 percent, vs. colonic J-pouch, 2.3 percent); or anastomotic complications: (coloanal anastomosis, 7/39 (17.9 percent), vs, colonic J-pouch, 2/44 (4.5 percent) P = 0.08); strictures: (10.3 vs. 0 percent); leaks: (5.1 vs. 2.3 percent); bleeding: (2.6 vs. 0 percent); rectovaginal fistula: (0 za 2.3 percent). Also, in the colonic J-pouch group, two patients developed pouchitis, and one patient experienced difficult evacuation one year after surgery. There was a statistically significant better function judged by less frequent bowel movements (4 +/- 2 vs. 2.4 +/- 1.3/day; P < 0.005) and urgency (36.7 vs. 7.7 percent; P < 0.05), incontinence score (2.2 +/- 3.7 vs. 0.8 +/- 1.6; P < 0.05) up to one year after surgery. At two years, the coloanal anastomosis group did not show statistical improvement in functional results compared with one year postoperatively. Rectal compliance in manometric findings was significantly increased in the coloanal anastomosis group at one year after surgery (12.4 +/- 12.6 vs. 4.2 +/- 1.5 ml/mmHg; P < 0.05). However, these differences were less profound after two years. CONCLUSION: The functional superiority of the colonic J-pouch was greatest at one year after surgery. By two years, adaptation of the "straight" coloanal anastomosis yielded similar functional results. However, the almost fourfold reduction in anastomotic complications in the colonic J-pouch group reveals a second potential advantage of this technique.