Primary myelofibrosis is a clonal disease of chronic myeloproliferative neoplasm, and is a progressive clinical course with short median survival of less than 5 years after diagnosis. Leukemic transformation occurs in 8-23 % of myelofibrosis patients, and survival is about 3 months after transformation to leukemia. Thalidomide, an oral immunomodulatory drug, has been used effectively in the treatment of primary myelofibrosis, in which some patients could become transfusion independent, and showed improvement in thrombocytopenia and reduction in spleen size. Here, we report a patient with primary myelofibrosis with leukemic transformation who survived for more than 6 years with thalidomide monotherapy. Thalidomide may be beneficial for some myelofibrosis patients with leukemic transformation for whom intensive chemotherapy is not indicated.