The renocortical idex(RCI) is a number expressing the fraction of the area of the whole kidney which isoccupied by the cavitary system and it is calculated by dividing the product renal length times width by theproduct length times breath of the cavitary system. Normal intravenous pyelograms of 232 cases taken at ChungnamNational University Hospital for recent two years were analized. The following results were obtained. 1. The sizeof kidney in male is larger than in female and right kidney is smaller than the left. 2. The ratio of renal lengthto the height of second lumbar vertebral infemale is lightly higher than in male. 3. The mean RCI of hte rightkidney is 0.345±0.035, the left kidney is 0.0351±0.038. 4. There is no significant difference between the RCI ofright and left, and in 57% of the cases both kidneys show the RCI of same value. 5. The difference of RCIaccording to sex, height of patient and renal length is not seen. However, the RCI is increased with age.