Background & Objective: Oral health care in adolescent is important for oral health of adult life. The aim of this study was to investigate knowledge and attitude on oral health among high school students. Method: A questionnaire survey was conducted in April, 2010 for students of two high schools located in Yangsan, Gyeongsangnam-Do, Korea and final data from 458 students was analyzed. Results: The study subjects were well known about toothbrushing but not on scaling, oral care products, and fluorine. They had positive attitude toward toothbrushing, regular oral health examination, and smoking and drinking control but assumed negative attitude to scaling and utilization of fluorine. A total of 51.1% of the study subjects has participated in oral health education and they had higher level of knowledge and attitude on oral health. There was a significant difference in knowledge and attitude on oral health according to the interest level in oral health and also in knowledge on oral health according to self-rate oral health status. According to utilization of oral health product and scaling knowledge and attitude level on oral health were different significantly. Conclusions: Knowledge and attitude of adolescent are necessary to be improved and changed in some topics of oral health through oral health education.