Bone metastases are a severe problem in oncology, since they usually are associated with pain. External beam radiation therapy (EBRT) has been, for many years, an important component of the treatment regimen to relieve pain. We have performed a clinical study to evaluate the relationship of response to EBRT in terms of pain relief and improvement in quality of life (QoL). We were also interested in the incidence of acute toxicity with EBRT. We have prospectively evaluated 75 patients (median age 68 years, range 64-79 years) with bone metastases from prostate cancer treated with EBRT, radiographically documented from June 1999 to September 2000. Additional therapies in these patients included: second-line hormonal therapy (HT) in 20 patients, chemotherapy (CT) in 25 patients, biphosphonates in 45 patients. For all patients a pain and narcotic evaluation was done before entering the study. Assessment of response was carried out by evaluating pain relief. QoL was measured by using the EORTC QLQ-C30 questionnaire. Toxicity analysis was based on the ROTG grading system. Survival was calculated by Kaplan-Meier estimate from the start of EBRT treatment until the last follow-up or death. A total of 61 out of 75 patients (81%) experienced some type of pain relief after treatment. The complete response rate was 23%. No significant difference in the response rates was found between the group treated with EBRT alone versus the groups treated with EBRT + CT or EBRT + HT. We noted a significant improvement in some of the scales of the considered EORTC-QLQC30 questionnaire. As expected all treatment-related complications were either grade 1-2 acute or subacute and transitory in nature. The group treated with EBRT + CT experienced slightly higher toxicity rates. There were no treatment-related fatalities. Forteen patients of 61 (23%) responders was alive at 12 months. Our results confirm the ability of EBRT to relieve bony pain in the majority of the cancer patients treated as measured by prospective analysis of pain scales prior to and after EBRT. Minimal side effects were experienced and QoL improved as shown by the results of the specific questionnaire.