Human parotid saliva contains many acidic proteins which are genetically determined. Studies have indicated that certain acidic salivary proteins absorb onto enamel surfaces, and that these proteins could be involved in the organization and development of the plaque matrix. The purpose of this study was to investigate the possible influence of salivary phenotype on individual proclivity to develop dental plaque, periodontal disease and/or caries. Each subject was clinically examined to determine their DMFS score, periodontal and dental plaque indices. A parotid saliva sample was collected for phenotyping. Pr and Db salivary phenotypes were analyzed with data obtained from 63 Caucasian subjects by one-way analysis of variance. Subjects that were phenotypically Db plus had a significantly (P less than 0.05) higher plaque index and higher periodontal index than Db- individuals. Thus far correlations were not discerned between Pr phenotypes and clinical observations. Chi-square analysis showed a disproportionate number of individuals with both Pr 1-2' and Db-phenotypes. There are indications that Caucasian individuals with the Db plus phenotype are more prone to developing dental plaque with concurrent periodontal disease.