To evaluate the effect of obesity on serum leptin and insulin levels in 80 elementary school children (aged 10.8 yr, 47 boys, 33 girls), we collected the anthropometric data and measured serum leptin and insulin levels. Serum leptin level and insulin resistance are known as factors which are associated with obesity and obesity related diseases such as diabetes, cardiovascular disease, hypertension. The results were as follows. The serum levels of insulin (p＜0.001), leptin (p＜0.001) and HOM $A_{IR}$ (p＜0.001) in obese group were significantly higher than those of other groups. The obesity indices correlated significantly to serum levels of insulin and leptin, but not to fasting glucose level. These results suggested that circulating leptin and insulin concentrations may act as a humoral signal indicator to adiposity-associated metabolic disorder in elementary school children.