This is the final analysis of Protocol #78-10 which explored increasing single-doses of half-body irradiation (HBI) in patients with multiple (symptomatic) osseous metastases. When given as palliation, HBI was found to relieve pain in 73% of the patients. In 20% of the patients the pain relief was complete; over two thirds of all patients achieved better than 50% pain relief. The HBI pain relief was dramatic with nearly 50% of all responding patients doing so within 48 hours and 80% within one week from HBI treatment. Furthermore, the pain relief was long-lasting and continued without need of retreatment for at least 50% of the remaining patient's life. These results compare favorably with those obtained by the Radiation Therapy Oncology Group (RTOG) using several conventional daily fractionated schemes on similar patients in a prior study (RTOG #74-02). HBI achieves pain relief sooner and with less evidence of pain recurrence in the irradiated area than conventionally treated patients. The most effective and safest of the HBI doses tested were 600 rad for the upper HBI and 800 rad for the lower or mid-HBI. Increasing doses beyond these levels did not increase pain relief, duration of relief, or achieved a faster response; however, the increase in dose was associated with a definite increase in toxicity. Single-dose HBI was well tolerated with no fatalities seen among 168 treated patients. A comprehensive premedication program has proven to decrease the acute radiation syndrome to very acceptable levels. There were excellent responses found in practically all tumors treated, but especially breast and prostate among which over 80% of all patients experienced pain relief, 30% in a complete fashion. Single-dose HBI emerges as one of the safest, fastest, and more effective palliative tools for intractable cancer pain in modern radiation oncology.