It is generally accepted that the CT is an extremely accurate means to obtain more definite informations onthe diagnosis of renal masses, although the conventional excretory urography remains the primary tool in thediagnosis of renal disorders. The authors studied 62 cases of proven renal disordors among 758 abdominal CT scansperformed during the period from Oct. 1977 to Jan 1980 in Kyung Hee University Hospital. The resuls were asfollows; 1. Of 23 simple renal cyst cases, 20 cases were found incidentally and 17 of them were over 50 years ofage. 2. The CT scan have proved to be an extremely accurate means in differentiation benign renal cyst fromneoplastic origin; based on attenuation value, demarcation from normal renal parenchyme and thickness of wall,especially the attenuation value. 3. CT scan holds great promise in diagnosing renal tumors, especially in stagingof tumor and determining surgical feasibility and its approach. 4. Pathology and its extension of retroperitonealspace was demonstrated accurately by CT and cause of nonfunctioning kidney could be often explained withoutretrograde pyelography. 5. Associated polycystic changes in liver, spleen and pancreas to polycystic kidney waseasily diagnosed by CT alone.