A 4-week energy balance study was conducted to estimate the energy expenditure (EE) of 16 primary school age boys and girls, 8 to 12 year age, by measurement of energy intakes and changes in body energy (BE) content (intake / balance technique), keeping their normal living pattern and eating behavior. Gross energy intake (GE) and fecal energy (FE) loss was measured by bomb calorimetry. Urinary energy (UE) loss was calculated from nitrogen excreted. Fat mass (FM) was determined from body density estimated from skinfold thickness. Mean constitutional ratio of carbohydrate, protein and fat for the total energy intake was 10.1 $pm$1.8%, 12.2$pm$0.1% and 17.1$pm$2.0% for the boys and 74.0$pm$1.7%, 10.7$pm$0.3% and 15.3$pm$0.5% for the girls, respectively. Fecal energy loss was 5.1% and 4.5% proportion of the gross energy intake for the boys and girls, respectively. Mean daily metabolizable energy estimated by subtract feral and urinary energy loss was 1862$pm$15kcal for the boys and 1627$pm$20kcal for the girls. Total body energy change estimated from body composition change over 28 days was increased 1524$pm$539kcal for the boys and 3622$pm$718kcal for the girls. Mean daily energy expenditure was 1812$pm$37kcal(52 $pm$2kcal/kg of body weight) for the boys and 1487$pm$25kca1 (52$pm$2kcal/kg of body weight) for the girls.