The application of standard radiographs (metastatic series) and radionuclide scanning in the serial evaluation of patients treated for metastatic osseous lesions is reviewed. False positive interpretations of bone scans are related to the inability to distinguish osteoblastic healing response from osteoblastic response to progressive tumor. False negative scans are uncommon and are related generally to symmetrical osteoblastic activity or to inadequate (subthreshold) osteoblastic response to tumor. Standard radiographs are preferable to bone scans in the serial evaluation of the effectiveness of therapy for osseous metastases in that anatomic quantitation of lesions as well as the dynamic evolution of lytic lesions to "blastic" healing may be appreciated. Serial bone scanning should be performed in conjunction with standard radiographs of abnormal areas of radionuclide accumulation.