OBJECTIVES: PEGIFN beta-1a is the first pegylated interferon beta-1a administered subcutaneously every two weeks, indicated for the therapy of relapsing remitting multiple sclerosis (RRMS). The objective of this analysis was to estimate the potential economic impact following due of the introduction of PEGIFN beta-1a in Italy.  METHODS: The analysis was conducted with a three-year time horizon with the support of a decision-analytic model adopting the perspective of the Italian National Healthcare Service (NHS). Healthcare costs sustained by the Italian NHS for the management of the RRMS population (drug treatment, monitoring, relapse management, adverse event management) were calculated over 3 years and compared for two scenarios: i) The current scenario where only interferon beta and glatiramer acetate are RRMS patients available and ii)  An alternative scenario after the introduction of PEGIFN beta-1a. The RRMS population was estimated to be approximately 35,500, 37,500 and 39,500 patients at Year 1, 2 and 3 respectively, based on published epidemiology literature and market data. The efficacy of treatments was simulated as reduction of relapse rates and was derived from a mixed treatment comparison. Unit costs were based on Italian 2015 prices and tariffs, and the published literature. A one-way sensitivity analysis was developed. RESULTS: According to current price and reimbursement conditions established by the Italian NHS, the introduction of PEGIFNb-1a will result in cost savings. This model found that PEGIFN beta- 1a would provide in related of treating RRMS patients  an estimated annual costs of €318,800,000, €336,100,000 and €353,600,000 in Year 1, 2, and 3 respectively compared to the costs of the current scenario of €319,200,000, €337,200,00 and €355,200,000 in Year 1, 2, and 3, respectively. The cumulative budget reduction over the three year period was €3,100,000 (an approximate 0.3% savings).  CONCLUSIONS: The adoption of PEGIFN beta-1a for the treatment of RRMS is economically sustainable by the Italian NHS.