Twenty patients with massive trichuriasis were studied with double contrast barium enema. The following changes were observed: 1) Impregnation defects of the colonic wall probably due to abundant mucous secretions. 2) Granular features. 3) Pear-shaped caecum. 4) Radiolucid ringlike images with some contrast material in its center, similar to those seen in lymphoid hyperplasia. On closer observation it was seen that the radiolucid ring was not complete and was continued by a prolongation which corresponds to the whipworm. This feature is central to the differential diagnosis.