For (18)F-FDG-PET/CT and for (99m)TC-MDP, sensitivity, specificity, accuracy, PPV and NPV for detecting all studied bone metastases were 88.3, 83.6, 86.7, 91.7, 77.8% and 91.7, 71.0, 84.9, 86.6, 80.8%, respectively. For bone metastases of breast and lung cancers, the specificity and accuracy of PET/CT was higher than that of bone scintigraphy. On the other hand, the sensitivity of bone scintigraphy was higher than PET/CT in breast and lung cancers groups and all patients