To review the previous preventive measures against the incidence of dental caries in children, we started to examine the state of dental health in children at the age of 18 months. The annual dental examination continued up to 12 years of age (sixgraders). Enrolled in this study were a total of 225 children living in a Town T and born between 1980 and 1982.Meanwhile, we made surveys in order to gauge the degree to which the subjects and their parents have concern for oral health. The findings and their relationships to the caries incidence were analyzed using an epidemiological technique. The annual dental examinations revealed that in primary dentition the incidence of caries tends to increase in 3·year-olds while in permanent dentition the carious process extends in 4-6 graders.By kind of teeth, primary molars accounted for 52% of the affected deciduous teeth. First molars made up 72% of all the decayed permanent teeth.Using the two caries cumulative indexes developed by our department for recording the prevalence and severity of tooth decay in the deciduous dentition and in the permanent dentition, respectively, we found that there is a correlation between the incidence of caries in the deciduous dentition and that in the permanent teeth.The two formulae are based on the cumulative number of decayed teeth that appeared in the deciduous dentition and permanent dentition for a given period of time.In order to find whether there is any correlation between caries attack and attention paid to the risk factors, we divided the subjects into two groups by the number of decayed teeth per person. In the group made up of those with many carious teeth, it was noted that between-meal snacks are most likely to produce caries in deciduous teeth, while lifestyle affects permanentteeth.