This study was conducted in order to determine width, length of lung by radiographic method. The measurements carried out on normal chest X-ray film of 1,036 persons who took the radiograph from the April of 1977 to the June of 1978. As a result of this study, the following conclusions were obtained: 1. In the case of male, the average width, and length of both side lung size from new birth to nineteen of age was larger than female with the exception of partly age group. 2. Lung size in average width at adult was from 27.60cm to 29.20cm and female was 25.10cm to 26.22cm. 3. The mean length of left lung at adult was from 26.32cm to 25.27cm in female. 4. The average length of right lung at adult was from 25.8cm to 28.35cm in male and female was from 24.86cm to 25.17cm. 5. It was found that lung sige in width and length was slightly increased until 39 years of age, but was trend to decrease it of lung in the age of 40 years old. 6. In the case of adult, the difference of the average length between right and left lung, the length of right lung was slightly shorter than left that.