Polycythaemia vera (PV) is associated with a reduced quality of life, a high rate of vascular events, and an intrinsic risk of disease evolution. The results of several randomised trials for the treatment with new cytoreductive agents are now available, among which a new ropegylated formulation of interferon alfa-2b (ropeginterferon alfa-2b) have been recently approved in Europe and USA \[EMA (2019), FDA (2021) and AIFA (2022)\]. The use of this drug in clinical practice is an opportunity for a prospective observational study in a rare disease such as PV; the aim is to evaluate its impact in the practical management of these patients. Therefore, the main objectives of the present study are to determine: (i) to what extent ropeginterferon alfa-2b can be prescribed and tolerated in patients with PV; (ii) the risk-benefit of ropeginterferon alfa-2b in patients with PV, followed-up in real-world clinical practice.