Uterine leiomyosarcoma associated with the paraneoplastic production of granulocyte-colony stimulating factor (GCSF) is extremely rare. No case has been reported to date in the English literature. We describe a case of a 56-year-old female with recurrent uterin leiomyosarcoma, associated with leukocytosis (19100/mm3) and an elevated serum GCSF (33.0 pg/ml). Tumore histology was consistent with a well differentiated leiomyosarcoma with marked neutrophilic infiltration of the lung and spleen metastases. tumor cells were distinctly positive for GCSF on immunohistochemistry. These findings confirmed the diagnosis of a GCSF-producting uterine leiomyosarcoma with a paraneoplastic leukocytosis.