Objective: To observe the clinical efficacy and adverse reactions of ruxolitinib in the treatment of high risk primary myelofibrosis. Methods: In July 2017 and September,2 patients with primary myelofibrosis who were diagnosed as high risk in Qiqihar First Hospital were examined for blood routine,spleen and body weight changes before and after oral administration. Results: 2 patients were followed up for 5 ~ 7 months. The spleen was reduced,body weight increased and the consumptive symptoms disappeared. Con...