A specific family of glycolipids, the globoseries, was shown to act as receptors on human uroepithelial cells and erythrocytes for the majority of uropathogenic Escherichia coli strains attaching to or hemagglutinating those cells. This was demonstrated in three different ways: (i) correlation between the natural presence of glycolipid in the target cell (erythrocytes of different species) and binding of bacteria; (ii) inhibition of attachment to human uroepithelial cells by preincubation of bacteria and glycolipid; and (iii) induction of binding to unreactive cells by coating of these cells with glycolipid. Strains reacting with the receptor agglutinated guinea pig erythrocytes in a mannose-resistant way after, but not before, coating of the cells with globotetraosylceramide. Unrelated glycolipids were not recognized. The reaction was made independent of simultaneous occurrence of mannose-sensitive adhesions on the strains by addition of D-mannose. The receptor-coated cells were used as a tool to screen for prevalence of receptor recognition in a collection of 453 E. coli strains isolated from patients with urinary tract infection or from the stools of healthy children. Of 150 strains attaching to human uroepithelial cells and agglutinating human erythrocytes, 121 bound to globotetraosylceramide (81%). Globoside recognition was especially frequent among pyelonephritis strains (74/81). The glycolipid composition of the urogenital epithelium and kidney tissue and the ability of uropathogenic E. coli to bind to these glycolipids may be a determinant in host-parasite interaction leading to urinary tract infection.