OBJECTIVES Biosimilar infliximab has been approved by EMA for the management of inflammatory autoimmune disorders including rheumatoid arthritis (RA), ankylosing spondylitis (AS), Crohn’s disease, ulcerative colitis (UC), psoriatic arthritis (PsA), and psoriasis based on quality, safety and efficacy profiles comparable to infliximab. The aim of this study was to evaluate the five-year budget impact of introducing biosimilar infliximab in the management of RA, AS, Crohn’s disease, UC, PsA, and psoriasis from the healthcare system perspective. METHODS An Excel-based budget impact model was developed. The numbers of patients eligible for infliximab were calculated based on disease prevalence rates in Germany, Italy, Belgium, the Netherlands and the United Kingdom. The price of biosimilar infliximab is not yet known; therefore three discount scenarios versus infliximab (10%, 20%, and 30%) were applied. Market share was assumed to be 25% in the first year in all scenarios. Annual market share growth was varied in each of the scenarios at 20%, 30% and 40%, respectively. RESULTS The combined net budget savings for Germany, Italy, Belgium, the Netherlands and the United Kingdom in the first year were €17.8, €35.5 and €53.3 million for the 10%, 20% and 30% price discount scenarios, respectively. Over a 5 year period the net budget savings were €132.8, €322.8 and €532.8 million for the 10%, 20% and 30% price discount scenarios, respectively. CONCLUSIONS The introduction of biosimilar infliximab as a treatment option for patients with RA, AS, Crohn’s disease, UC, PsA, and psoriasis could achieve substantial cost savings for healthcare systems. In the price discount scenarios tested, the total combined savings across Germany, Italy, Belgium, the Netherlands and the United Kingdom over a 5 year period ranged from €132.8 million to €532.8 million. The net budget impact was highly sensitive to market uptake rates and the price discount applied.