The role of different cell surface components in the adhesion ofStreptococcus pyogenes to pharyngeal cells was investigated. No difference between parental strains and Mnegative mutants in adhesiveness was detected. Purified lipoteichoic acid markedly inhibited adhesion of group A streptococci. A similar inhibitory effect was observed with group B streptococci andStaphylococcus, aureus strains. All the A-variant streptococci tested demonstrated decreased adhesion ability. In particular, the A-486 strain, with a temperaturedependent variation in the synthesis of the group-specific carbohydrate, adhered less when cultured at nonpermissive temperature (38°C). No effect of growth temperature on lipoteichoic acid synthesis was detected. Preincubation of epithelial cells with group-A-specific polysaccharide greatly decreased the number of bacteria per cell that adhered. These results suggest that C polysaccharide might be specifically involved in the adhesion of group A streptococci.