BACKGROUND: Whereas allergic disease has a high morbidity among adolescents, there have been few reports concerning asthma prevalence using objective parameters such as methacholine bronchial provocation tests in this age group. OBJECTIVE: Thus we investigate the prevalence of asthma and other allergic diseases using questionnaires and measuring bronchial hyperresponsiveness (BHR) in high school students in Korea. METHOD: A questionnaire survey was conducted among 1499 high school students, from 3 regions in Korea between April and May, 2006. They responded to a modified International Study of Asthma and Allergies in Childhood (ISAAC) written (WQ) and video (AVQ) questionnaires. 709 subjects of them underwent methacholine bronchial challenge test. RESULT: The WQ showed that the lifetime and 12- month prevalences of wheeze were 16.0% and 8.9%.The lifetime prevalence of asthma diagnosis was 7.0% and 12-month prevalence of asthma treatment was 1.5%. By video questionnaire, the lifetime prevalence and 12- month prevalence of wheeze were 7.9% and 5.5%. The prevalence of current asthma based on the questionnaire and bronchial challenge tests was 3.2%. The prevalence of current asthma and BHR were higher in female than in male subjects. For 12-month prevalence of allergic rhinitis and atopic dermatitis were 37.7% and 11.4%, respectively. CONCLUSION: The prevalence of current asthma in high school students were 3.2%. Despite the fact that 12-month prevalence of wheeze and lifetime prevalence of asthma diagnosis were 8.9% was 7.0%, only 1.5% of answered subjects received asthma treatment. Its prevalence was still low compared to asthma prevalence.