Purpose: This study was conducted to estimate the prevalence of asthma and its risk factors in childhood asthma. Method: Random samples of 10,236 were selected from 43 kindergarten (1,418) and 57 elementary (8,718) in K city between september and November (2007). 1,079 (kindergarten children) and 7,271 (elementary children) were in the final analysis. The Korean-translated modified version of the questionnaire for the International Study of Asthma and Allergies in Childhood was used in this cross-sectional survey. Parents were surveyed to answer for the questionnaire. Result: The lifetime and 12-month prevalence of wheezing were 11.50%; 11.06% in kindergarten children and 19.24%; 4.80% in elementary children. The lifetime prevalence of asthma diagnosis and the 12-month prevalence of asthma treatment were 11.59%; 4.43% in kindergarten children and 4.43%; 10.78% in elementary children. The 12-month prevalence of night cough and exercise-induced wheezing were 12.90%; 3.33% in kindergarten children and 20.72%; 4.74% in elementary children. Risk factors analysis showed that age, paternal and maternal asthma, allergic disease, carpet use, monthly income, indoor environment were associated with a higher risk of asthma. Conclusion: The study suggests that prevalence of asthma has increased among the community children. These data have been used to manage a possible role of risk factors as predictors of childhood asthma.