The main cause of local recurrence after curative operation for rectal cancer is intra-operative implantation of viable shed cancer cells. The present study was undertaken to investigate whether irrigation of remnant rectum prior to anastomosis would prevent local recurrence in rectal cancer. Remnant rectum was irrigated 20 times with physiologic saline using 30 ml enema syringe. One hundred thirty-five patients with rectal cancer underwent sphincter-saving resection for cure. Twenty-six of these patients, received irrigation with physiologic saline, and the remainder received no irrigation. Viable cancer cells were still present in remnant rectum after irrigation 10 times, but absent after 20 times. Distribution by age, sex, stage and the distal clearance margin was similar in both groups. Local recurrence occurred in none of the irrigation-treated patients and in 11 percent of the untreated ones (p less than 0.05). Our results indicate that irrigation 20 times with 30 ml of physiologic saline of the remnant rectum prior to anastomosis is an effective method of preventing local recurrence after resection of rectal cancer.