A comparison of the sensitivity of detection of metastatic bone disease by the bone scan and skeletal roentgenogram in 100 patients revealed a higher yield from the bone scan alone (86%) than from the roentgenogram alone (73%). In the tumor groups which frequently have osseous metastases (breast, prostate, and lung), the bone scan was greater than 95% accurate. Moreover, in patients with positive findings from both procedures, additional lesions were detected by the scan which were not demonstrated by the roentgenogram in 29%. A significant number of false negatives were encountered with both procedures when the entire group was examined. The greatest yield was obtained by employing both techniques.