In 1992, dental health examination was conducted in three areas in Korea; Seoul (large city), Cheonan (rural city) and Cheongju (water fluoridated rural city). We also examined the children of Tokyo in Japan. The subjects were the schoolchildren in the 6th grade of primary school and the 3rd grade of junior high school, and the number of the subjects was 202 in Seoul, 191 in Cheonan, 164 in Cheongju and 152 in Tokyo. We compared the oral health status among these four areas using many indices such as the prevalence rate of dental caries and malocclusion, DMFT, DMFS, DI-S and P-M-A index. In Korea the children in Seoul showed the highest caries prevalence rate, DMFT and DMFS. The Cheonan children were average. The children in Cheongju had the lowest caries experience. The children in Tokyo had more dental caries than the Korean children in both school grades. The children in Tokyo had more gingivitis and malocclusion than the Korean children in the three areas. It was revealed that the oral health status of the Korean schoolchildren was much better than the Japanese children. And water fluoridation project in Cheongju was effective to prevent the dental caries especially in the 6th grade children.