OBJECTIVES: In February 2016, the first etanercept biosimilar (EtnBS) has been launched in Germany, which may represent a cheaper option to the original biologic agent (EtnBA). The objective of this study was to provide initial real-world data on the penetration of EtnBS within the EtnBA market by evaluating switching dynamics between the two drugs in real world clinical practice. METHODS: Patients receiving first EtnBS prescription, with or without previous treatment with EtnBA, were retrospectively identified using the Longitudinal Prescriptions database (QuintilesIMS® LRx) between January 2008 (beginning of database) and September 2016 (last available data). The representativeness of the database based upon current population and pharmacy coverage in 2016 is around 60% of the statutory health insurance market. For patients with prior EtnBA treatment, the mean treatment duration prior to switch was reported. In addition, the proportion of those who switched back to EtnBA and the mean time to switch were evaluated. For all patients, the drug device used was recorded. RESULTS: A total of 1,536 patients on EtnBS (62% using pens and 38% pre-filled syringe) were identified, of which, 813 (52%) had, on average, around 3 years of prior treatment with EtnBA. Among these, the large majority were using pre-filled syringe (70%) and kept the same kind of device when switching to EtnBS (61%). After changing to EtnBS, a total of 65 patients (8%) switched back to EtnBA after only 2 months. The 72% of the patients who switched back to EtnBA chose the same kind of device (pre-filled syringe). CONCLUSIONS: Despite many patients change from etanercept to its biosimilar treatment, 8% switch back to the original biologic agent in the short term. Longer term studies are required to confirm these preliminary results and investigate the reasons for changing back to the original product.