BACKGROUND: The aim of this study was to investigate the prevalence of food allergy (FA) and determine its risk factors in the preschool urban children in Seoul, Korea. METHODS: A modified International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire was used to survey 933 pre-school children from nine urban areas of Seoul in Korea. The risk factor analysis was done by logistic regression analysis. RESULTS: In preschool children, the lifetime and recent 12-month prevalence of FA symptoms were 21.0% and 10.6%, respectively. The lifetime prevalence of FA diagnosis was 6.1%, the prevalence of current FA (12-month symptoms and diagnosis) was 3.3%, and the recent 12-month prevalence of FA treatment was 3.6%. Blood eosinophils  in FA group and Non-FA group were 5.00+/-3.93% and 3.93+/-2.91%, respectively (P=0.002). The median total Immunoglobulin E (IgE) of FA group was 102 (interquatile [IQ] range 44.8-257) IU/mL, the median total IgE of Non-FA group was 70.9 (IQ range 70.9-161) IU/mL (P=0.001). Parental FA (adjusted odds ratio [aOR], 2.17; 95% confidence interval [CI], 1.22-3.85), past history of AD diagnosis (aOR, 3.69; 95% CI, 2.33-5.85), eczema on doctor's physical examination (aOR, 3.74; 95% CI, 2.16-6.47), use of antibiotics during infancy more than 3 days (aOR, 1.72; 95% CI, 1.08-2.73) were the independent risk factors for FA symptoms within 12 months. CONCLUSION: In preschool urban children in Seoul, the lifetime prevalence of FA diagnosis was 6.1%, the recent 12 month prevalence of FA treatment was 3.6%. The prevalences of AD and doctor examined AD in FA group were significantly higher compared to Non-FA group. Family history, and the use of antibiotics during infancy could be the independent risk factors for the development of FA.