A high percentage of naïve granulocytes is often indicative of a myeloproliferative neoplasm and can also be seen in patients with granulocyte colony-stimulating factor. A high percentage of naïve granulocytes can be a sign of myelodysplastic syndrome or acute leukemia. Myelodysplastic syndrome occurs when the percentage of naïve granulocytes in the bone marrow is less than 20%, and acute leukemia occurs when it is greater than 20%. The use of granulocyte colony-stimulating factor (GCSF) in some post-chemotherapy granulocyte-deficient patients can also lead to elevated naive granulocytes, which disappear when GCSF is discontinued, and no special treatment is needed in this case. If granulocyte colony-stimulating factor is not used, it is recommended to consult the hematology department for the cause of the high percentage of naive granulocytes.