In an attempt to determine whether "high ligation" of the inferior mesenteric artery during surgery for cancer of the rectum and rectosigmoid confers any significant 5-year survival advantage over "low ligation," the outcome of 1370 patients was reviewed. There were 784 patients in whom the inferior mesenteric artery was ligated below the origin of the left colic artery (low ligation) and 586 in whom it was ligated above this level (high ligation). The distribution of histologic grades of the tumors and incidence of venous invasion were similar in both groups. Five-year follow-up was complete in 98.5%. No difference in the crude or age-corrected 5-year survival was found for patients with Dukes A, B, C overall, or C1 tumors, whether having had a low or high ligation. In hopes of identifying a population that benefited from high ligation, C1 patients were further subgrouped according to tumor location and number of involved lymph nodes. However, in no such subgroup was any significant high ligation advantage seen. In conclusion, high ligation of the inferior mesenteric artery has not been found to improve 5-year survival in patients with cancer of the rectum or rectosigmoid.