In the eastern part of Java and on the island of Bali betel chewing is a very common habit confined principally to females. The purpose of the present study was to examine the influence of betel chewing on the prevalence of dental caries. The study, which is based upon 982 villagers, indicates a strong inverse relationship between the prevalence of dental caries and the intensity of betel chewing. The possible mechanisms whereby betel chewing may have a caries-inhibiting effect are discussed.