OBJECTIVES: The main aim of this study was to analyse the budget impact of introducing biosimilar infliximab for the treatment of rheumatoid arthritis in six central European countries’ –Bulgaria, Czech Republic, Hungary, Poland, Romania and Slovakia - healthcare systems.  METHODS: This budget impact model estimates the potential impact of the biosimilar infliximab on the healthcare budget over a three year time frame. The model considers third-party payer perspective. A spreadsheet-based country specific dynamic population model was developed. The model functioned in quarter year time units according to the three months long evaluation period. The model tracked the movement of the RA population between main states: 1) on synthetic DMARD, 2) on infliximab, 3) on biosimilar infliximab, 4) TNF inhibitors other than infliximab and 5) biologics other than TNF inhibitor. Switching between biologics and biosimilar infliximab was taken into consideration too. Scenario analyses were conducted, different rate of interchanging and switching were considered. A -25% percentage price difference was assumed for biosimilar infliximab compared to originator infliximab. The budget impact was calculated as the difference in the total cost of the scenarios with and without biosimilar infliximab in each year of the model. RESULTS: Over the entire 3-year period with gradually interchanging 80% of infliximab patients to biosimilar infliximab is expected to leading to a net benefit of 29,810,000 euros compared to the scenario in which biosimilar infliximab would not be available. In the scenario in which interchangeabilty was disallowed the budget savings was 18,765,000 euros. If budget savings were spent on reimbursement of additional biosimilar treatments, approximately 1,615 or 1,025 more patients could be treated in the six countries, respectively. CONCLUSIONS: This budget impact analysis indicates that introducing biosimilar infliximab might result significant budget savings or increasing of the number of patient access to biological therapy. Interchanging by prescribing physicians could substantially increase budget savings.