A total of 146 patients were investigated for the presence of osseous metastases with 99mTc polyphosphate or 99mTc pyrophosphate bone scans. Results of bone imaging were retrospectively compared to roentgenographic results surveying similar anatomic areas in 128 patients. This comparison revealed that roentgenographic interpretations were in error in 19% of the cases. Thirty-three patients had bone scans and roentgenograms that were in agreement and considered abnormal, but in more than one third of these cases the patients had multiple abnormalities that were shown by the bone scan but were not recognized roentgenographically. In consideration of the low toxicity, ready availability, economy, shortened procedure time, and low radiation dose associated with the use of these new bone-seeking agents, it is concluded that they are superior to roentgenograms and previously utilized radionuclides for early detection of osseous metastases.