Bone scans with Tc-99m-MDP were analysed in 179 patients with various type of malignant tumor who treated in Severance hospital from June 1980 to January 1981 . The brief results were follows 1. Among the 179 cases, bone scans were positive in 111 cases(62%), while only 35 cases(34%) were positive in roentgenogram. 2. In cases of positive bone scans and roentgenograms, there showed significant correlation with bone pain but no correlation with the level of serum calcium and alkaline phosphatase. 3. Distribution of metastases sites on bone scan revealed that no specific location in each malignant tumors, but prostate cancer showed some prevalance on pelvic cavity. 4. In comparison of bone scan and roentgenogram, abnormal bone scan was more accurate and sensitive than usual roentgenogram in early detection of bone metastqses in malignant tumors.