The renocortical index(RCI) is a number expressing the fraction of the area of the whole kidney which is occupied by the cavitary system and it is calculated by dividing the product renal length times width by the products length times breath of the cavitary system. Normal intravenous phyelograms of 232 cases taken at Chungnam National University Hospital for recent two years were analized. The following results were obtained. 1. The size of kidney in male is to larger than in female and the right kidney is smaller than left. 2. The ratio of renal length to the height of second lumbar vertebra in female is slightly higher than in male. 3. The mean RCI of the right kidney is 0.346$pm$0.035, the left kidney is 0.351$pm$0.038. 4. There is no significant difference between the RCI of right and left, and in57% of the cases both kidneys show the RCI of same value. 5. The difference of RCI according to sex, height of patient and renal length is not seen. However, the RCI is increased wit age.