Rheumatoid Arthritis, Ankylosing Spondylitis, Psoriatic Arthritis and Psoriasis determine a high cost to the Italian National Health Service (INHS). The availability of biological drugs – among which etanercept – greatly improved treatment efficacy. The biological drugs are an expensive resource. Etanercept patent protection has expired, and biosimilar has been recently approved. Considering the perspective of the INHS, a drug budget impact (DBI) analysis was conducted to evaluate the consequences of the biosimilar availability in terms of cost containment (savings), thanks to its lower price compared to the originator’s. The DBI model expects that some patients in treatment with the originator will switch (uptake rate) to the biosimilar and that some naïve patients will directly start treatment with the biosimilar (uptake rate). Separately considering all the different diseases for which etanercept is indicated (Rheumatoid Arthritis, Ankylosing Spondylitis, Psoriatic Arthritis and Psoriasis), the number of patients who might potentially use the biosimilar is estimated – based on disease prevalence and incidence rates, the overall proportion of treated patients and the etanercept market share. The time horizon extends to five years. The results from the analysis show (in the base case) that the availability of the biosimilar would provide overall annual savings over €25 million to the INHS in the fifth year, while the cumulated savings in the five years period would be about €90 million.