Seventy-five patients with sessile adenomas or early carcinomas of the rectum or rectosigmoid were operated on with the new technique “transanal endoscopic microsurgery” Employing a newly developed complex endoscopic operating system, complete removal of sessile adenomas can be accomplished up to a distance of 25 cm from the anal verge, accurately and non-invasively. Complications occurred in three cases, with no resulting mortality. In the follow-up period we discovered only one adenomatous recurrence that required operative treatment. The superior accuracy of preparation, a short average stay in hospital, and low recurrence and complication rates are the advantages of this transanal endoscopic operative technique.