Objective To investigate the prevention of gangrene of exteriorized colon following transabdomino-perineal saving sphincter resection of rectal cancer. Methods From Aug. 1988 to Feb. 2000, 46 cases of cancer of the rectum were treated by transabdominoperineal saving sphincter with severing the anal sphincters and anorectal ring. During this procedure the anal sphincters and anorectal ring were severed to prevent gangrene of the exteriorized colon. Results In these cases, the exteriorized sigmoid colon had good blood supply and no gangrene was found. Conclusion This method can effectively prevent the gangrene of exteriorized sigmoid colon stump and gives no permanent fecal incontinence.