A 67-year-old male patient who was diagnosed with primary myelofibrosis 4 years ago did not respond to conventional therapies. The splenomegaly progressively increased, which caused spleen infarctions and led to the decision to perform a splenectomy procedure. After splenectomy, the patient started treatment with ruxolitinib. In the first month of ruxolitinib treatment, the patient became transfusion-free and all constitutional symptoms disappeared. However, in the sixth month of ruxolitinib treatment, the disease transformed to acute myeloblastic leukemia, and the patient died 1 month later. This is the first case report that shows the effects of ruxolitinib in a splenectomized patient.