Background: To describe treatment patterns and costs of care associated with the use of FDA-approved agents for metastatic castrate-resistant prostate cancer (mCRPC). Methods: Two large integrated claims databases (MarketScan, PharMetrics) were used to identify males ≥ 18 years old diagnosed and treated for prostate cancer (ICD9 = 185.xx or 233.4) with bone metastases (ICD9 = 198.5) from 06/2013 to 09/2014. Patients were required to be continuously enrolled ≥ 6 months pre- and post-initiation of treatment with abiraterone, cabazitaxel, docetaxel, enzalutamide, mitoxantrone, radium-223, or sipuleucel-T. Results: There were 953 and 565 patients meeting all inclusion criteria in each database, with a median follow-up time of 18 and 14 months, respectively. Mean age was 69 to 71 years. Prior to mCRPC treatment initiation, 14.0% to 18.2% of patients received radiation therapy, 36.1% to 40.0% denosumab, 16.5% to 16.8% zoledronic acid, and 0.2% to 0.8% pamidronate. Across both databases, abiraterone was most commonly received agent across all lines of therapy, except fourth line (Table 1). The median cost per patient per month during the post-index period was $10,292 to $10,916 in the each database, respectively, compared to $2,643 to $2,742 per patient per month during the 6-month pre-index period. Conclusions: Patients were treated mainly with abiraterone across most lines of care, with bone-targeted therapy being used in < 3% of patients. Median costs per patient per month increased approximately ~$8,000 over this period.