This study was undertaken to examine relations between obesity and birthweight, parental weight and serum biochemical levels(lipids , glucose, insulin and aminotransferase) in elementary school children aged 10-12 . The weight of obese girls was higher than that of obese boys, while WHR was higher in obese boys than in obese girls. The birth weight of the obese children was significantly higher than that of the non-obese children(p<0.01), and was positively correlated with current weight. The concentrations of serum TG, LDL, VLDL, LDL-cholesterol, glucose, insulin and ALT in obese children were much higher than those in non-obese children . However, the serum HDL -cholesterol concentration of the obese children was significantly lower compared with that of the no-obese children. On the other hand, little differences in these levels were found between genders. The concentrations of PL, TC and AST in the groups showed no significant differences. In the obese children, serum concentrations of TG, LDL-cholesterol , glucose and ALT were more closely associated with GMI than with WHR. No significant correlation was found with serum insulin , glucose and TG levels. These data show that childhood obesity may be related to hyperlipidemia , atherosclerosis, hypertension, diabetes mellitus and fatty liver.