[en] Purpose: External beam radiotherapy (RT) is commonly indicated for the palliation of symptomatic bone metastases, but there is evidence of underutilization of this treatment modality in palliative care for cancer populations. This study was conducted to investigate factors that influenced the use of palliative RT services at a regional comprehensive cancer center. Methods and Materials: A cohort of patients with radiographically confirmed bone metastases and first-time users of palliative RT between 2003 and 2005 was retrospectively reviewed from the time of initial diagnosis of bone metastases to death or last follow-up. Type of radiation treatment service provider used (rapid access or routine access) and patient-, tumor-, and treatment-related factors were analyzed for their influences on the number of treatment courses given over the duration of disease. Results: A total of 887 patients received 1,354 courses of palliative RT for bone metastases at a median interval of 4.0 months between courses. Thirty-three percent of patients required more than one RT course. Increased age and travel distance reduced the likelihood and number of treatment courses, while service through a rapid access clinic was independently associated with an increase in subsequent use of palliative RT. Conclusions: A rapid access service model for palliative RT facilitated access to RT. Travel distance and other factors remained substantial barriers to use of palliative RT services. The pattern of practice suggests an unmet need for symptom control in patients with bone metastases.