The kidney size and its movability on the change of position from supine to erect by radiographic measurement provide an important value in the diagnosis and treatment of the renal disease. The lengh of the kidney, the ratio between the kidney length and the total height of the upper three lumbar vertebrae including intervertebral disc, the movable range of kidney in change of position from recumbent to erect and the distance from the left hilum to the right hilum were measured on intravenous pyelograms of 87 males and 97 females of the age of 20 to 59 years. The following results were obtained: 1. The radiographic measurement of kidney size and its movable range: {{{{sex }}{{age }}{{right kidney }}{{left kidney }}{{hilum(cm) }}{{length(cm) }}{{M(cm) }}{{K(ratio) }}{{length(cm) }}{{M(cm) }}{{K(ratio) }}{{male }}{{20-59 }}{{12.4$pm$0.76 }}{{2.8$pm$1.57 }}{{1.08$pm$0.07 }}{{12.7$pm$0.84 }}{{2.7$pm$1.46 }}{{1.12$pm$0.08 }}{{1.3$pm$1.37 }}{{female }}{{20-59 }}{{12.0$pm$0.98 }}{{3.5$pm$1.52 }}{{1.13$pm$1.10 }}{{12.4$pm$0.97 }}{{3.0$pm$1.45 }}{{1.16$pm$0.10 }}{{1.1$pm$1.24 }} }} (M: The mean of the movable range of kidney in change of position from supine to erect) (K: The ratio between the length of kidney and the total height of the upper three lumbar vertebrae including disc) 2. The size of kidney in male and the right kidney was smaller than in female and the left one, and mean difference was 0.3-0.4 cm. But the right kidney was larger in 25% of the cases than the left one. 3. The length of kidney was larger in 90% of the cases than the total height of the upper three lumbar vertebrae including disc. 4. The motion range of kidney in the change of position from supine to erect was 0-8.2 cm and the moving distance of the kidney in the right side and female was a little greater than that in the left kidney and male. 5. In 3% of the cases the kidney moved more than 6 cm in change of position from supine to erect. 6. The right hilum was usually lower in position than the left one. However, in 24 cases (13%) the right hilum was observed to be higher than the l ft one.