It is generally accepted that the computed tomography is an extremely accurate means to obtain more definite Information on the diagnosis of renal masses, although the conventional excretory urography remains the primary tool int he diagnosis of renal disorders. The authors studied 62 cases of proven renal disordors among 758 abdominal CT scans performed during the period from Oct. -1977 to Jan-1980 in Kyung Hee University Hospital. The results were as follows ; 1. Of 23 simple renal cyst cases, 20 cases were found incidentally and 17 of them were over 50 years of age. 2. The CT scan have proved to be an extremely accurate means in differentiating benign renal cyst from neoplastic origin ; based on attenuation value, demarcation form normal renal parenchyme and thickness of wall, especially the attenuation value. 3. CT scan holds great promise in diagnosing renal tumor니 especially in staging of tumor and determining surgical feasibility and its approach. 4. Patholigy and its extension of retroperitoneal space was demonstrated accurately by CT and cause of nonfunctioning kidney could be often explained without retrograde phyelogrpahy. 5. Associated polycystic changes in liver, spleen and pancreas to poly cystic kidney was easily diagnosed by CT alone.