Three-phase radionuclide bone scan, consisting of a radionuclide angiogram, an immediate postinjection bloodpool image, and 4th delayed images, was randomly performed in 182 patients, who had been suffered from eitherlocal pain or tenderness. Authors analysed 3 phase bone scan in 74 paitents with correct diagnosis provensurgically or clinically, from July,1987 to August, 1988. The results were as follows; 1. Overall sensitivity of 3phase bone scan was 85.4%: sensitivity in patients with an osseous lesion was 90.4% as opposed to 72.7% inpatients with a nonosseous lesion. 2. There was no difference in the detection rate of the osseous lesions betweenthe 3 phase bone scan and the delayed image bone scan. However, because the detection rate was higher on the 3phase bone scan than it was on only the delayed image bone scan(55%) in instances of the nonosseous lesion, wewould suggest that 3 phase bone scan might be obtained in cases suspected of the non-osseous lesions. 3, When thepresumptive diagnosis was a bone tumor, sensitiviity and spcificity for malignancy were 67%, 100% respectively. 4.In differentiating osteomyelitis from cellulitis, sensitivity was 94%, specificity was 100%, 5. 3 phase bone scanwas able to provide the precise information about either vasculaturity of localization of lesion in some cases ofsoft tissue mass and avascular necrosis of hips.