RESUMEN
Malnutrition, overweight and obesity are major health concerns in modern societies and especially among children. Overweight and obesity affect children's current and future health. It is known that the prevalence of overweight differs by race, sex, and geographic location. In a cross-sectional study 30092 Iranian children aged 7-18 years in six ethnic groups were selected by a cluster sampling. Prevalence of obesity and overweight and distribution of body mass index [BMI] by gender, age, and ethnicity were measured. Cutoff points of BMI for defining obesity and overweight were based on the Iranian, and IOTF standard values. This study showed a significant ethnic difference in BMI. Prevalence of overweight and obesity among Iranian children was 9.27% and 3.22% respectively comparing international standards. The frequency of overweight and obesity was higher in boys. This study showed a significant difference in BMI among different ethnic group