OBJECTIVES: We describe the usage of different biologic agents in Japan over time and try to identify factors that affect the decision to initiate treatment with biologic agents. We also analyse determinants of a switch to another biologic agent for patients who are already on biologic treatment. METHODS: We utilize a hospital claims data base with 36504 Japanese patients with a confirmed RA diagnosis. To analyse the determinants of treatment choices, we apply logistic regression analysis taking socio-demographic and medical factors into account.    RESULTS: CONCLUSIONS: The lower likelihood of elderly patients to be switched to a biologic might be due to risk aversion of Japanese physicians’ and patients who are afraid of potential side effects of biologics. This finding is also consistent with the notion of an age bias that impedes elderly patients from optimal access to biologic treatment.