Excretory urography defines the collecting system and shape of the kidneys. Radioisotope scanning complements this procedure, as it assesses the mass of proximal convoluted tubules. The close correlation of the two technique leads to improved diagnostic accuracy. The renal scan with neohydrin and excretory urography of 100 cases were performed at the same time in renal disease at the Severance Hospital. Proof of diagnosis was based upon renal angiography, biopsy, operation, or special laboratory tests decisive for diagnosis. The results obtained were as follows: 1. In patient with proven intrinsic masses, the scan has been confirmatory but non-specific. The scan can be helpful when excretory urograms show no abnormality in patients of renal hematoma or renal carbuncle. 2. Renal scan with Hg-203 neohydrin is a good technique for detecting functioning renal tissue that is not apparent on excretory urograms. And it is good for preoperative screening test. 3. In renal failure, int rpretation of right kidney is confused due to increased concentration of radioactivity in the liver in scintillation scanning with Hg-203 neohydrin. 4. The scintiscan has also been additional aid in establishing the diagnosis of congenital anomaly such as polycystic kidney, horse-shoe kidney, hypoplasia, and agenes of kidney.