The role of strontium chloride Sr 89 in the palliative treatment of pain associated with metastatic bone disease is reviewed. Conventional therapies to relieve metastatic bone pain include nonopioid and opioid analgesics, hormonal therapy, external-beam irradiation, and chemotherapy. Limitations in the long-term safety and effectiveness of these treatments have increased interest in using systemic radioactive isotopes for palliation of pain. Strontium chloride Sr 89 is a relatively new bone-seeking radiopharmaceutical that has FDA-approved labeling for use in relieving pain associated with skeletal metastases. An analogue of calcium, strontium chloride Sr 89 is rapidly cleared from the blood after i.v. injection. The agent selectively irradiates metastatic sites while generally sparing normal soft-bone tissue. In clinical studies, a majority of patients with prostate or breast cancer obtained substantial relief from bone pain after receiving strontium chloride Sr 89 alone or in combination with external-beam irradiation. Adverse effects tend to be mild, but patients should be monitored for possible hematologic toxicity. Patients should discontinue any calcium-containing products before receiving the agent. The typical dose is 4 mCi (148 MBq) administered by slow i.v. push over one to two minutes; doses can be repeated at three-month intervals. Pain relief usually begins in 10-20 days and lasts up to six months. Radiation safety measures are necessary in handling strontium chloride Sr 89 and the wastes of patients. Strontium chloride Sr 89 is costly, but preliminary analysis indicates that it may reduce management expenditures overall.(ABSTRACT TRUNCATED AT 250 WORDS)