Hematologic paraneoplastic alternations may not be very common, but they have been observed in a small number of patients. Granulocytosis has been described in several malignancies and its common mechanism may be associated with granulocyte colony-stimulating factor (G-CSF) production by the tumor. High neutrophilia (150,000-240,000 white blood cell count) observed in two patients with non-small cell lung cancer led us to run the present trial. The purpose of this study was to compare the white blood cell counts and the G-CSF plasma levels of the patients and classify the results into groups, as well as to determine the survival rates of the patients in each of the groups. The histological specimens and plasma of two patients as well as the plasma of another 87 patients with several malignancies, were examined. The plasma G-CSF levels were determined using a quantitative sandwich immunoassay technique (Quantikine; RySD systems) according to the manufacturer's instructions and all samples were tested in triplicate. It was found that 12 patients had a white blood cell count increased beyond normal as well as a high G-CSF plasma level and the survival of these patients was shorter as compared to the rest of the patients. We assume that these findings may indicate that increased G-CSF levels may function as a biomarker of survival.