OBJECTIVES: The objective of this study is to evaluate cost-effectiveness of abiraterone plus prednisolone compared to prednisolone alone in Japan. We presented the result of the cost-effectiveness analysis of abiraterone acetate in 2013 ISPOR Europe Congress. In the present study we reanalyze the cost-effectiveness of abiraterone by referencing the real world resources using a Japanese claim data set. METHODS: Cost-effectiveness analysis was performed using a Markov model based on data from the randomized controlled trial (COU-AA-301 study) and literature review conducted from the public healthcare payer’s perspective. The abiraterone plus prednisolone was compared with prednisolone alone. The base case was assumed to be a 72 year-old man with metastatic castration-resistant prostate cancer (CRCP). The model used a time horizon of 10 years. Outcomes were measured in quality-adjusted life years (QALYs), and incremental cost-effectiveness ratio (ICER) was calculated. As Japanese Ministry of Health, Labour and Welfare has not yet approved abiraterone due to the delay in development, the drug cost was estimated based on prices in four other countries. In the present study, resource use was estimated using a Japanese claim data set with 2000 claim data of prostate cancer patients from January 2005 to March 2013. Both cost and outcomes were discounted at a 2% annual rate. RESULTS: The result of this study revealed that abiraterone plus prednisolone indicated higher QALYs than prednisolone alone. In the base-case analysis, ICER for abiraterone plus prednisolone exceeded JPY 17 million (roughly EUR 120,000) per QALY gained. One-way sensitivity analysis for the price of abiraterone influenced ICER (JYP 12.5 - 21 million). CONCLUSIONS:  The present study suggested that the ICER is more than JPY 10 million. Further deliberate discussion on cost-effectiveness of abiraterone in Japan is needed to consider the Japanese price and clinical outcomes.