Some of these substances are glycoproteins giving reactions of antigenic identity with carcinoembryonic antigen (CEA) derived from colorectal carcinoma and occur in aggregation with proteins showing antigen specificities of albumin, haptoglobin and the heavy chains of immunoglobulins G, A and M. Recoveries of CEA-like activities, following Sepharose 4B chromatography of urinary materials of molecular size > 3 × 104, varied from 40 to 1530%. Here, CEACAM5 is linked to colorectal carcinoma.