We have investigated the role of lipoteichoic acid in mediating the adherence of different serotypes of group B streptococci to human adult and neonatal epithelial cells. Pretreatment of neonatal buccal and vaginal epithelial cells with lipoteichoic acid, but not with deacylated lipoteichoic acid, induced a marked inhibition in the adherence of all strains tested. Pretreatment of bacteria with substances known to bind lipoteichoic acid, such as monoclonal and polyclonal antipolyglycerophosphate antibodies and albumin, also resulted in adherence inhibition. Group B streptococci adhered in 6- to 10-fold-higher numbers to buccal epithelial cells from neonates older than 3 days than to those from neonates less than 1 day old. This increase in receptiveness for group B streptococci was paralleled by an increased ability of epithelial cells from older neonates to bind group B streptococcal lipoteichoic acid. These data suggest a role for the lipid portion of lipoteichoic acid in the adherence of different serotypes of group B streptococci to vaginal and neonatal epithelial cells.