A safe and practical procedure for total colectomy and mucosal proctectomy with ileoanal anastomosis has been developed and performed by us on 11 patients with adenomatosis coli and two patients with ulcerative colitis. The major features of the operative procedure are 1) total removal of the rectal mucosa to just above the dentate line; 2) preservation of anorectal function by a long rectal cuff procedure achieved by rectal mucosal excision from a level just below the sacral promontory, using a rectal internal stent and gauze packing techniques for rectal mucosal stripping, with, in some patients, an ileal reservoir added; and 3) prevention of pelvic sepsis by intraoperative rectal irrigation, rectal cuff drainage, and a temporary defunctioning loop ileostomy. Of six patients with at least three months of follow-up after reconstruction, each has returned to normal life, averaging two to seven semiformed stools each day. A side-to-end ileoanal anastomosis with a low-lying, loop-type ileal reservoir provided the best functional results.