The radiographic measurement of the renal size position provide important information of diseases of the kidney and the adjacent organs. The author analyzed the 213 cases of intravenous pyelography of normal Korean children from 0 to 18 years of age (135 males and 78 females) and measured the following points ; the length of the kidney, the width of the kidney, the level of both hila, and the ratio of the kidney length to the total height of upper 4 lumbar vertebral bodies plus intervertebral discs. The results were obtained as follows ; 1. Above 4 years of age, the annual increase rate of the kidney length was 0.31cm, and that of the height of lumbar vertebrae was 0.44cm in male and 0.55cm in female ; the height of lumbar verterbrae grew more rapidly than the kidney length. 2. The age group of the most rapid growth in the length and the width of the kidney was 16 to 18 years of age in male, and 13 to 15 years of age in female, and that of the most delayed growth was 4 to 6 years of age in both sexes. 3. The size of the left kidney was usually larger than that of the right. But, the right kidndy was larger than the left in 20% of the cases. 4. The right hilum was usually lower than that of the Left. In the 12% of the cases, however, the right hilum was higher in position than the left. 5. The width of the kidney in most children corresponded to the 45 to 60% of the kidney length. 6. The kidney size in age group between 16 and 18 years was within the range of that of normal adults. 7. The ratio of the kidney length to the height of upper 4 lumbar vertebral bodies plus intervertebral discs were as follws : > 1.1 below 3 years of age. 1$pm$0.1 between 4 and 12 years of age. < 0.9 above 13 years of age.