AbstractFamilial adenomatous polyposis (FAP) includes early development of up to thousands of colorectal adenomas and of colorectal adenocarcinoma in all untreated cases. Moreover, a variety of extracolonic manifestations are seen. Proctosigmoidoscopy is used for screening; when adenomas are found, the diagnostic evaluation includes colonoscopy and gastroduodenoscopy. Screening of first degree relatives should start at the age of 10 years, using proctosigmoidoscopy at regular intervals. The recent detection of a specific FAP gene at chromosome 5 and of congenital retinal pigmentations will allow an early preclinical diagnosis in the future. A centralized registration of FAP has resulted in an improved prognosis, and the establishment of international groups will contribute to increased research of this disease.