By definition, polyposis of the colon is a condition in which adenomatous tumor grows from the wall of the bowel and projects into the lumen. Most authors adhere to the classification of Erdmann and Morris,1 which divides polyposis into two types: (1) the adult or acquired type, which usually follows a chronic inflammatory process, such as chronic ulcerative colitis, tuberculosis or amebiasis; (2) the familial type, which involves the entire colon and rectum of young adults and shows a definite hereditary tendency. It is with this second type that this study is concerned. The condition of polyposis was first described by Virchow2 in 1863, and Cripps3 presented 2 cases in 1882 in which he noted the hereditary factor. Since that time many studies have been published in the literature, and the heredofamilial malignant aspect of some cases has been emphasized. McKenney4 studied three family groups, a