Aim: Dual-energy X-ray absorptiometry (DXA) is considered a reference method for adiposity measurements in epidemiologic studies. The purpose of this study was to evaluate the influence of gender, age, and physique in the relationship between body mass index (BMI) and DXA derived adiposity indices for Korean children and adolescents. Methods: Using a nationally representative sample taken from the Korean National Health and Nutrition Examination Survey (KNHANES), 2009 to 2011, BMI of Korean children and adolescents was compared with DXA determined adiposity indices (fat mass index, FMI and percentage body fat, PBF). The correlation was subsequently evacuated according to the genders, age groups (children aged 10-12.9 yrs, early adolescents aged 13-15.9 yrs, and late adolescents aged 16-18.9 yrs.) and BMI level (< or ≥85th percentile for age and sex). Results: In 1919 (1024 boys) Korean children and adolescents, BMI was more strongly correlated with FMI than PBF (r = 0797 and r = 0.519, respectively all study subjects, P < 0.05), across all age groups, gender, and physiques. Conclusions: BMI is more highly correlated with FMI than PBF in Korean children and adolescents.