['At present, the treatment of polycythemia vera (PV) and essential thrombocythemia (ET) is still largely supportive and symptomatic. Homoharringtonine (HHT), a valid drug for treating chronic myelogenous leukemia, has shown some effect on leukemic stem cells. The aim of this study was to observe the effect of HHT on patients with high-risk PV and ET.', 'Patients with high-risk PV (n = 17) or ET (n = 18) who had failed or were intolerant to hydroxycarbamide or interferon-α therapy received HHT at a dose of 1.5 mg/m(2) daily by continuous infusion for 7 days every month. Hematological responses were evaluated at the 6th month after HHT therapy.', 'After six courses of HHT therapy, the hematological response rates were 64.7 % (11/17) in PV and 72.2% (13/18) in ET. In PV, the single sign remission rates of constitutional symptoms, symptomatic splenomegaly, pruritus and bone pain were 70.0% (7/10), 77.8% (7/9), 50% (1/2) and 100% (3/3), respectively. The remission rates of constitutional symptoms and symptomatic splenomegaly in ET were 66.7% (6/9) and 71.4% (5/7), respectively. The rates of grade 1 granulocytopenia and thrombocytopenia were 1.8 and 0.9%, respectively. No grade 2 or over events, or pancytopenia were observed.'] Is homoharringtonine an effective therapy for patients with polycythemia vera or essential thrombocythemia who have failed or were intolerant to hydroxycarbamide or interferon-α therapy?