Objectives : To assess the seroprevalence and risk factors of toxoplasmosis in high school students in Cheju Province, Korea. Methods : A total of 4,570 high school students from 18 schools in Cheju Province were investigated for Toxoplasma gondii antibodies(IgG) by enzyme linked immunosorbent assay (ELISA). Risk factors for toxoplasmosis, such as place of residence, type of house, contact with cats and other pets, and rare meat consumption, were examined by questionnaire. Results . The overall antibody positive rate was 5.5% and ranged from 2.6 to 11.5% by school. There was no significant difference between males and females. Statistical analyses of the questionnaire data indicated that the risk factors for seropositivity were: (1) birth place (Cheju/others), (2) place of residence (rural/urban), (3) dietary habits (vegetarian/non vegetarian), (4) eating rare meat, (5) exposure to pets and (6) hepatitis B. Conclusion : We confirmed that the prevalence of the anti-Toxoplasma gondii antibody in a population of high school students in Cheju Province was to the previously reported prevalence.