Purpose: This study examined the distribution of the body mass index (BMI) according to gender and age among Korean children and adolescents to compare the distributions of being underweight, normal, overweight, and obese using both Korean and international criteria. Methods: This secondary data analysis utilized the data of the 2016 Korean National Health Examination for School Students Height, weight, and BMI distributions among children and adolescents were analyzed using descriptive statistics, and the differences in BMI distribution according to gender and age were analyzed using chi-square tests. Differences in the mean BMI according to the Korean Centers for Disease Control (KCDC), the World Health Organization (WHO), and the International Obesity Task Force (IOTF) criteria were analyzed using ANOVA. Results: Using the IOTF criteria, the prevalence of underweight, overweight, and obesity among grades 1-12 students was 6.7%, 20.8%, and 7.1%, respectively; 1.6%, 21.3%, and 11.8%, respectively, according to the WHO criteria; and 5.8%, 10.1%, and 13.0%, respectively, according to the KCDC criteria. Conclusion: It is recommended to use the IOTF criteria for health promotion programs to target underweight children and adolescents while the WHO and KCDC criteria should be used for health programs for treating obese people.