The effects of high molecular weight mucins, adsorbed on enamel and artificial solid substrata with various surface free energies, on oral streptococcal adhesion have been investigated. For the adhesion studies, 3 strains of oral streptococci with widely different surface free energies were used. The substrata were precoated with mucins with a molecular mass >105 Da. The adhesion of S. mutans NS to mucin coated, hydrophobic FEP‐teflon was significantly increased by the presence of the mucin coating, whereas the adhesion of S. mutans NS to more hydrophilic substrata such as cellulose acetate, glass and enamel decreased. In addition, the adhesion of S. sanguis 12 and S. mitis BMS to mucin‐coated surfaces decreased slightly. However, adhesion of S. sanguis to FEP‐teflon remained unaltered. Unlike S. mitis, S. mutans and S. sanguis are known to possess specific carbohydrate receptor sites (lectins) which may interact with the carbohydrate part of adsorbed mucins. From the decrease in the adhesion of S. mutans to mucin‐coated glass, it is concluded that mucins adsorb to glass with their polar carbohydrate part. On the other hand, it is hypothesized that mucins adsorb to FEP‐teflon with their apolar protein part, thereby revealing their carbohydrate part towards the solution phase and stimulating the adhesion of S. mutans NS, while leaving the adhesion of S. sanguis 12 unaltered. Further evidence for this adsorption model of mucins is provided by contact angle measurements. [ABSTRACT FROM PUBLISHER]