&NA;A new method for the surgical treatment of ulcerative colitis and polyposis coli is described. Instead of preparing a pelvic pouch, the natural rectal pouch stripped of the diseased mucosa was used experimentally in dogs. The undisturbed muscular cuff of the rectum (12 cm from the anal verge) was covered by healthy vascularized mucosa of small bowel in such a manner that the dog could use its rectum as usual before surgery. The results are encouraging. The rectal reservoir is spared, with its sensitivity, continence and motor activity covered by healthy mucosa. The dogs thrived.