Determination of the total lung capacity (TLC) has been widely used in the evaluation of the pulmonary function. The measurements and calculations of the total lung capacity by radiographic method is a relatively simple procedure by which physicians can obtain data regarding the total lung capacity. The total lung capacity was measured and calculated by radiographic method in 270 cases of normal school children, 168 males and 102 females. The following results were obtained. 1. The value of TLC in male was larger than that in female in the same age, height and weight group. The mean value of TLC in female was 86.7% of that in male. 2. TLC tended to increase as height increased, the correlation coefficient(r) being 0.81 with standard deviation of$pm$871ml in male and$pm$727ml in female and it had an approximation to the value of 1 Ht3 in male and 0.8 Ht3 in female. 3. the TLC tended to increase slightly as weight increased, the correlation coefficient (r) being 0.84 with standard d viation of$pm$871ml in male and $pm$727ml in female. 4. Measurement of roentgenogram as regards TLC determination is relatively simple, rapid and accurate.