Polycythemia vera (PV) is a chronic myeloproliferative disorder whose major morbidity and mortality are thrombohaemorragic events. Current guidelines advise maintaining hematocrit (HCT) level below 45% in males and 42% in females. Such targets lean on pathophysiological reasoning, while evidence from ECLAP and PVSG-01, the two largest prospective studies in this disease, suggests no difference in the rate of thrombosis in patients maintained at different HCT values below 50%-52%. Cytoreductive therapy in PV (CYTO-PV) is a multicenter, randomized, and controlled trial assess the benefit/risk profile of cytoreductive therapy with phlebotomy or HU aimed at maintaining HCT < 45% versus maintaining HCT in the range 45%-50%. CYTO-PV is being conducted in the framework of the Gruppo Italiano Malattie Ematologiche nell'Adulto (GIMEMA) and is funded by the Italian Drug Agency (AIFA). It is an independent trial with broad recruitment criteria to mimic clinical practice. We describe here the study and its advancement status. Conclusions. Clinical research in rare disease can be carried out with limited funds, provided a research hypothesis is felt as clinically relevant by a scientific community willing to share knowledge on the outcome of clinical practice, thus producing scientific results useful to improve treatment and prognosis of patients.