A case of chronic neutrophilic leukemia (CNL) is reported. The patient had a history of bleeding, and showed sustained mature neutrophilic leukocytosis, hepatosplenomegaly, a high leukocyte-alkaline phosphatase score, elevated serum vitamin B12 and uric acid, and the presence of Döhle bodies in the neutrophils. In addition to the above typical features, marked myelodysplastic changes in the erythroid and megakaryocytic series were observed in the bone marrow. Three months after the diagnosis of CNL had been established, the hematological picture evolved into a blast crisis of monocytic type. Such findings give support to the statement of CNL as a distinct entity belonging to the spectrum of the myeloproliferative disorders.