The aim of this study was to evaluate the teaching of cariology in Japanese dental schools.Postal questionnaires were sent to all Japanese dental schools.Twenty-five of the 29 Japanese dental schools (response rate: 86%).The results were in many areas similar to those reported from North America. The non-surgical approach to the management of primary caries predominated, but no schools used bacteriological tests in caries diagnosis and only one school recommended antibacterial treatment. Four of the 25 responding schools advocated the treatment of primary enamel lesions by surgical intervention while three awaited operative intervention until the lesions had reached the middle third of the dentine. Recommendation of fluoride treatment was less common than in North America. The use of electronic devices to diagnose occlusal caries lesions was more common than in North America, but 'explorer catch' was the most frequently used method to diagnose primary and secondary caries in dental schools in both regions.Research in cariology over the years has led to altered views on how and when to treat caries lesions. The interpretation of research findings and the transfer of knowledge by teachers in dental schools have an impact on the practice of operative dentistry, but the diversity in the teaching of cariology indicates that the interpretation and implementation of modern principles in the treatment of caries differ quite markedly in Japanese dental schools.