Introduction: Immune cells and molecules are considered as clinical biomarkers and potential targets for immunotherapy. Analyses of the composition of peripheral blood cells hold promise for providing a basis for diagnosing and prognosis lung cancer. In this study, we assessed correlations between immune cell subset profiles in peripheral blood and disease prognosis in patients with lung cancer. Methods: One hundred and thirteen patients with lung cancer and 99 age-matched healthy people were enrolled in this study. The percentage and cell count of monocytes, neutrophils, T cells, B cells, natural killer (NK), and NKT cells in peripheral blood were analyzed by flow cytometry or peripheral blood analyzer. Serum cytokines and colony-stimulating factors were detected by enzyme-linked immunosorbent assay (ELISA). Results: A reduction in antitumor NK cells (p < 0.0001) and an increase in the protumor MDSCs (p < 0.0001) were observed in the lung cancer patients compared with the controls. Monocyte counts were significantly higher in lung cancer patients with histories of smoking (p < 0.05) or drinking (p < 0.01) than in patients with no relevant history or healthy controls. The number of neutrophils and the neutrophil-to-lymphocyte ratio (NLR) were particularly higher in patients with liver metastasis (p < 0.01) compared with no metastasis patients or healthy controls. Levels of the monocyte-derived cytokine interleukin-6 (p < 0.05), granulocyte colony-stimulating factor (G-CSF) (p < 0.0001), and granulocyte-macrophage colony-stimulating factor (GM-CSF) (p < 0.0001) were higher in patients than in controls. G-CSF levels decreased during the remission phase (p < 0.05), and positively correlated with carbohydrate antigen 19-9 (p < 0.05) and gene mutation (p < 0.05). Conclusion: Monocyte and neutrophil counts were higher in peripheral blood in lung cancer patients than in controls, especially when patients had histories of smoking, drinking, and liver metastasis. Serum levels of G-CSF and GM-CSF were higher in lung cancer patients, and G-CSF levels positively correlated with disease severity.Keywords: granulocyte colony-stimulating factor; lung neoplasms; monocytes; peripheral blood.