['This open-label, prospective, observational study aimed to evaluate treatment response, efficacy therapy and safety to IFN α-2b for the essential thrombocythemia (ET) and polycythemia vera (PV) with JAK2V617F positive mutation.', 'A total of 123 ET patients received IFNα-2b therapy with JAK2V617F positive or negative mutation; and 136 PV patients with JAK2V617F(+) received IFNα-2b or hydroxyurea (HU) therapy according to random number assignment (ages 18-65 years old).', 'ET patients receiving IFN α-2b with JAK2V617F(+) had a greater advantage in overall hematologic response (OHR) than JAK2V617F(-) (83.3% versus 61.4%, P<0.01). For PV patients with JAK2V617F(+), IFN had no OHR superiority to HU (70.3% versus 70.8%, P>0.05), but which gained a greater satisfactory molecular response than HU (54.7% versus 19.4%, P<0.01). IFN significantly decreased the phlebotomy rate, which was better than HU for MPDs patients with OHR than HU (3.6% versus 65.7%, P<0.01). Furthermore, ET patients with JAK2V617F(+) demonstrated a definite advantage over JAK2V617F(-) in five-year PFS (75.9% versus 47.6%, P<0.05). For PV patients with JAK2V617F(+), IFN α-2b was superior to HU in five-year PFS (66.3% versus 46.7%, P<0.01). Moreover, IFN α-2b also contributed to improved vasomotor symptoms in MPDs, and especially significantly decreased the incidence of distal paresthesias (14.1% versus 37.5%) and erythromelalgia (9.4% versus 29.2%) better than HU (P<0.01). Meanwhile, IFN did not observe the severe hematological adverse events in patients with PV or ET.'] Does interferon α-2b gain high sustained response therapy for advanced essential thrombocythemia and polycythemia vera with JAK2V617F positive mutation?