Unexpected renal abnormality can be detected on bone scan using Tc-99m-MDP. The purpose of the study is to evaluate the diagnostic significance of diffusely increased bliateral renal uptake on bone scan. 1,500 bone scan were reviewed and 43 scans which showed diffusely increased bliateral renal uptake were selected for analysis. Laboratory findings for renal and liver function tests including routine urinalysis were reviewed in 43 patients. 26 of 43 case showed abnormality in urinalysis and renal function study. 20 of 43 cases showed abnormal liver function study and 3 of these cases were diagnosed as hepatorenal syndrome later. 13 of those 20 cases had liver cirrhosis with or without hepatoma. 12 of 43 cases showed abnormality both in renal and liver function studies. 2 of 43 cases showed diffusely increased bilateral renal uptake after chemotherapy for cancer but not on previous scans before chemotherapy. 2 of 43 cases showed hypercalcemia and 8 of 43 cases had multifocal bone uptake due to metastasis or benign bone lesion. but the latter showed no hypercalcemia at all. There was no significant correlation between increased renal uptake and MDP uptake in soft tissue other than kidneys. This study raised the possibility that the impaired liver and/or renal function may result in diffuse increase of bliateral renal uptake of MDP of unknown mechaninsm. It seems to need further study on this correlation.