Various Escherichia coli and Salmonella strains bound to glycoproteins of the family of carcinoembryonic antigens (CEA). As judged from plateau regions of the binding curves, CEA, nonspecific cross-reacting antigen of Mr 55,000 (NCA-55), and biliary glycoprotein of Mr 85,000 (BGP-85) showed similar binding activities. The binding to ovalbumin was significantly lower and the binding to fetuin was insignificant under identical experimental conditions. The binding of E. coli and S. typhi to the different glycoproteins was similar as judged from the binding curves. In comparison with alpha-methyl-D-mannopyranoside, aromatic alpha-glycosides of mannose were more potent binding inhibitors of E. coli but not of salmonellae to CEA and NCA-55. These results are similar to those previously obtained with intestinal epithelial cells and yeast cells (N. Firon, S. Ashkenazi, D. Mirelman, I. Ofek, and N. Sharon, Infect. Immun. 55:472-476, 1987). The binding of E. coli to CEA was inhibited by purified type 1 fimbriae. On the basis of the distribution of CEA-like glycoproteins in tissues and body fluids, the results indicate that glycoproteins of the CEA family may be involved in the recognition of bacteria and the regulation of bacterial colonization.