Definite tumor formations resulting from amebas have been reported so rarely that the observation of three cases within a period of six months appears unique. Scant attention has been given the fact that a localized tumor presenting the clinical and gross pathologic picture of carcinoma of the large bowel can be caused by amebas. Six similar cases are reported. Kartulis1mentions an instance in which the wall of the large bowel reached the astounding thickness of 22 cm. Runyan and Herrick2described four cases showing massive amebic thickening of the cecum. They mistook one of their four reported cases for a tumor of the kidney, and another for carcinoma of the cecum. They diagnosed correctly their two remaining cases on the basis of their previous experience and on the finding of amebas in the stool. Almost complete obstruction of the bowel was present, necessitating complete resection of the