Determination of the total lung capacity (TLC) has been widely used in the evaluation of the pulmonaryfunction. The measurements and calculations of the total lung capacity by radiographic method is a relativelysimple procedure by which physicians can obtaine data regarding the total lung capacity. The total lung capacitywas 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 thesame age, height and weight groupl. The mean value of TLC in female was 86.7% of that in male. 2. TLC tended toincreases as height increased, the correlation coefficient (r) being 0.81 with standard deviation of ±871 ml inmale and ±727 ml in female and it had an approximation to the value of 1 Ht3 in male and 0.8 Ht3 in female. 3. TheTLC tended to increase slightly as weight increased, the correlation coefficient (r) being 0.84 with standarddeviation of ±871 ml in male and ±727 ml in female. 4. Measurement of roentgenogram as regards TLC determinationis relatively simple, rapid and accurate.