Over 14 years 276 patients with rectal cancer underwent surgery; 219 who underwent low anterior resection of the rectum with total mesorectal excision were studied. There were 24 (11.0 per cent) major anastomotic leaks associated with peritonitis or a pelvic collection and 14 (6.4 per cent) minor leaks that were asymptomatic and detected by contrast enema. All major leaks occurred at an anastomotic height of less than 6 cm (P = 0.08). The abdominoperineal excision rate was 9.1 per cent. Major leaks were associated with failure to defunction in 11 of 62 patients and with a defunctioning colostomy in 13 of 157 (P = 0.03). Of the 24 patients with major leaks seven developed peritonitis, one with a defunctioned anastomosis (P = 0.002), and three died (P = 0.02). Use of the sigmoid colon led to major leakage in seven of 32 patients compared with 17 of 187 when the splenic flexure was employed (P = 0.05). There was no increase in the local recurrence rate but only nine patients with major leakage and a temporary stoma have had these closed. Key technical factors include: a clean dry pelvic cavity, pulsatile colonic blood supply, suction drainage started during closure and mobilization of ample tissue to fill the pelvic space.