Adhesive properties of Bifidobacterum bifidum strain DSM 20082 were studied by the hemagglutination test and an enzyme-linked immunosorbent assay (ELISA). B. bifidum caused agglutination of human A, B, and O erythrocytes and rabbit erythrocytes, but the interactions were not specific of blood group antigens. The hemagglutination was inhibited by porcine gastric mucin and rat intestinal and colonic mucin. B. bifidum was shown to adhere to different immobilized mucosal glycoproteins and to glycophorin A, a specific erythrocyte membrane glycoprotein. The data obtained with many glycosylated components indicated that B. bifidum receptors involved in the hemagglutination test were not the same as those that adhere to mucus glycoproteins. The results suggest that the mucosal preparations contain receptors for specific bacterial adhesins, but their structures remain to be determined.