Familial adenomatous polyposis (FAP) is an autosomal dominantly inherited disorder due to germline mutation of the tumor suppressor adenomatous polyposis coli (APC) gene, Multiple large bowel polyps usually develop in adolescenoe or early adulthood with inevitable progression to colorectal carcinoma. It is well known that patients with FAP are at considerable risk of developing extracolonic manisfestations of the disease. Particularly, desmoid tunors of the abdominal cavity, and duodenal adenomas and carcinomas are the most serious ones. Desmoid tumors and duodenal carcinomas are major muses of death in those patients in whom a prophylactic (procto) colectomy has been performed. We report the case of a 38-yeaz-old man with desmoid tumor and duodenal adenoma developing after total colectomy with ileostomy due fo FAP, and 1iferafures were reviewed. (Korean J Gastroietest Endosc 2001;23:32-35)