Authors enumerate various malignant and benign cases which showed soft tissue uptake of Tc-99m-MDP. We hope it might be a help in understanding and interpreting bone scans. Among 10,361 Tc-99m-MDP bone scans underwent from April, 1981 to March, 1986, 344 (3.3%) showed abnormal soft tissue uptake, which included 126 malignancies, 5 benign tumors, and 153 nontumorous diseases. Neuroblastoma (23.3%) and malignant fibrous histiocytoma (22.2%) showed highest positive uptake rate among various malignancies. We also illustrated typical cases according to possible mechanisms.