Objectives : The aim of the study is to investigate the oral health knowledge, attitude and dental caries experience in Korean 12-year-old adolescents. Methods : The subjects were 2,196 adolescents living in Seosan, with an average age of 12.2 years. Data were collected using a self-administered questionnaire from April 10 through June 10, 2011. A trained investigator made an oral examination of them in natural light, using a mirror and an explorer to determine their DMFT index. Results : The prevalence rate of dental caries of adolescents was 59.1%. The DMFT index of the subjects was 1.98, which was lower than the national mean of 2.2 for the same age. The DMFT index was significantly higher in the female(2.25) than the male group(1.72). The attitude of oral health was positively related to DMFT index in this study(OR=1.25; CI=1.01-1.54). It appears that knowledge and attitude concerning oral health, among young Korean 12-year-old adolescents living in Seosan, are in need of improvement. Conclusions : Based on the findings, dental caries experience is associated with attitude of oral health. This result suggests that the implementation of oral health promotion should be considered for various factors related to attitude of oral health in adolescents.