atients with diffusely increased uptake in both kindeys("hot kidney") on the Tc-99m-MDP bone imagings were evaluated. Total incidence of the "hot kidney" was 2.7%(56/2053). Among 56 patients with "hot kidney", the most common diseases were malignancies(30), and the remainders were composed of renal diseases(11) and other disease group(l6). We report the possible factors for the "hot kidney" with brief review of some literatures.