32P orthophosphate administered in a wide range of activity reduces or relieves the pain from osteoblastic metastases in approximately 80% of patients treated. The efficacy of this agent is equal to that of newer agents and of wide field radiotherapy, as documented in a literature review of 28 series reporting the use of 32P orthophosphate over a 50-year period. There is no dose-response relationship between the activity of 32P given and the percentage of patients experiencing pain reduction who received that activity. Only one death has been attributed to this radiopharmaceutical.