OBJECTIVES: A substantial proportion of prostate cancer care (PCa) is expected to be completed in the outpatient hospital setting, particularly as more hospitals systems acquire oncology practices. However, there is very limited information on practice-specific costs of care for patients receiving chemotherapeutic treatments within this unique setting. This study evaluated the cost of care for chemotherapy treatment in the outpatient hospital setting for PCa patients with bone metastases.  METHODS: Patients in the Premier Hospital Database between January 2006 and December 2010 treated in an outpatient setting for PCa (ICD-9-CM Codes 185 and 233.4) were selected. Patients were required to be ≥40 years of age and have no additional cancers and evidence of bone metastases (ICD-9-CM code 198.5 or the use of zoledronic acid or pamidronate disodium). Costs of care per visit across cost centers were evaluated and described. RESULTS: There were 5,223 outpatient visits for men treated for PCa with bone metastases. The mean age of the sample was 71 years, with 64% being Caucasian. The average visit cost was $4,614. Pharmacy costs ($4,119) represent 89.2% of total visit costs, followed by professional ($190) and laboratory expenses ($77). Chemotherapy costs represented 47% of total pharmacy costs, with the most commonly specified chemotherapies being docetaxel, mitoxantrone, and carboplatin.        CONCLUSIONS: Men treated for PCa with bone metastases treated in an outpatient setting averaged $4,614 per visit, with pharmaceutical costs representing almost 90% of care.