11 patients with juvenile polyposis and 4 patients with familial adenomatous polyposis after total colectomy entered the study. Long-term follow-up with endoscopic examination and multiple biopsies in these patients showed high probability of polyps in preserved regions of the gastrointestinal tract. Therefore, regular prophylactic endoscopy, morphological examinations and biopsies of endoscopically normal mucous membrane are justified. Such policy is recommended especially for patients with familial adenomatous polyposis.