Glucosyltransferases (GTF) and lipoteichoic acids (LTA) produced by S. mutans are implicated in the formation, of cariogenic dental plaque. Caries vaccine studies have indicated that protection against S mutans is associated with antibody to GTF, but vaccines also contain, at least LTA and/or dextranase. Immunization experiments using gnotobiotic rats suggest more protection with a vaccine of LTA/dextranase deficient in GTF than with one enriched for GTF. For further immunization studies, GTF has been purified free of LTA from a mutant of 6715 that apparently lacks dextranase activity. GTF, sucrase, and dextranase activities and LTA have been measured in monkey dental plaque. Highly purified LTA and antibodies produced against it are being used to study the role of LTA in S. mutans dental plaque formation. These studies are designed to gain insight into the biochemical and immunological aspects of dental caries which may lead to a rational approach for the control of this disease.