Eighty-three cases of renal cell carcinomas admitted to Nara Medical University and its related hospitals from August, 1962 through July, 1984 were reviewed. We have been using computed tomography (CT) and ultrasonography (US) for early detection of renal cell carcinomas since 1980. Thereafter the number of patients with low stage renal cell carcinoma was significantly increased. Furthermore 6 carcinomas were incidentally detected by CT and/or US examination for checkup of other diseases. We believe that CT and US may be valuable as a screening modality for early detection of renal cell carcinoma.