OBJECTIVES: A substantial proportion of prostate cancer care is expected to be completed in the outpatient hospital setting; however, there is limited information on the actual cost of care in this setting. The objective of this analysis was to evaluate the total annual costs of treatments for castration-resistant prostate cancer (CRPC) with bone metastases for the following agents: cabazitaxel, docetaxel, radium 223, and sipuleucel-T. METHODS: An economic model was developed from the hospital outpatient perspective with a 1-year time horizon. The expected cost of each treatment from the outpatient practice perspective was based on reported per-visit treatment costs, professional/administration costs, laboratory/monitoring costs, and allocated overhead costs. The total treatment cost per visit was multiplied by the annual number of expected treatment cycles to calculate annual treatment costs. Hospital-specific adverse event (AE) costs were applied to published grade 3 and 4 AE rates for each comparator and added to the total cost per treatment.  RESULTS: The total annual cost of therapy was lowest for docetaxel ($72,051), followed by radium 223 ($92,489), cabazitaxel ($93,742), and sipuleucel-T ($101,499). The treatment cost per visit was highest for sipuleucel-T ($30,936), followed by radium 223 ($12,362), cabazitaxel ($11,564), and docetaxel ($3,396). AE cost were $765 for sipuleucel-T, $5,123 for radium 223, $8,074 for cabazitaxel, and $11,223 for docetaxel.   CONCLUSIONS: Total annual costs for CRPC treatments ranged from $72,000 to $101,500 per patient.  Docetaxel had the lowest total annual costs, followed by radium 223, cabazitaxel, then sipuleucel-T, while sipuleucel-T had the lowest AE costs followed by radium 223, cabazitaxel, and docetaxel.