BACKGROUND: Recently, childhood obesity has increased and became a major health concern in Korea. The aim of this study is to measure the prevalence of childhood obesity in rural city and to explore the risk factors of obesity including obesity of parents. METHODS: We made 13 convenience samples of elementary school and attached kindergarten located in Asan-city, ChungNam, in 2001. We surveyed children's height, weight, and risk factors of childhood obesity with a self-recorded questionnaire answered by parents. Children's obesity was evaluated by ideal body weight which is defined as the 50th percentile of weight for Korean children of the same height and sex in 1998. The criteria of parents' obesity was over 25 of BMI. RESULTS: The subjects were 1,558 children among 1870 respondents. The prevalence of childhood obesity was 9.4% and that of male children was 11.0% and that of female children was 7.9%. The older in both male and female, the higher the obesity prevalence was. Mother's age were significantly higher in obese children. Birth weight and family income were also significantly higher in obese children. There was a higher family history of obesity in obese children. Risk factors associated with childhood obesity were gender, age of child, mother's age, birth weight, number of siblings, family income, and family history of obesity. CONCLUSION: The prevalence of childhood obesity in Asan-city was 9.4%. Children whose father, mother, or parents were obese tended to be obese.