It is possible that salivary proteins on bacterial cells have some influence on the adsorption of oral bacteria to the surface of oral tissues. The aim of this study was to clarify the influence of salivary proteins attached to the surface of Streptococcus sanguis ATCC 10556 (S. sanguis) on bacterial adsorption to hydroxyapatite beads treated with salivary proteins (S-HA beads). Just-harvested cells (N-system) and saliva-coated cells (C-system) were used.<BR>The results showed that adsorption to S-HA beads was gradually reduced by a covering of salivary proteins. No influence was observed on the adsorption of cells due to the presence of divalent cations, phosphate or EDTA when the N-system and C-system were compared. Though it was evident that hydrophobic bonding was involved in adsorption in the N-system, few such effects were observed in the C-system. Adsorption was inhibited to varying degrees by sugars in both systems. Pretreatment of cells with heat affected adsorption differently in the N-system and C-system.<BR>These findings suggest that salivary proteins attached to the bacterial cell surface may influence its adsorption to oral tissues.