Abstract: Objective To investigate the clinical significance of combined detection of insulin-like growth factor-1(IGF-1), Insulin-like growth factor blinding protein-3 (IGFBP-3), CEA and CA125 in the diagnosis of lung cancer. Methods The serum levels of IGF-1, IGFBP-3, CEA and CA125 in 77 patients with lung cancer and 41 healthy subjects were measured by chemiluminescence immunoassay and nephelometry. Results The serum levels of IGF-1 in patients with lung cancer were significantly higher than those in healthy subjects (P＜0.01). The serum levels of IGFBP-3 in patients with lung cancer were lower than those in healthy subjects (P＜0.05). The sensitivity in single detection of IGF-1, CEA and CA125 was 28.57%, 44.16% and 40.26%. The sensitivity in combined detection of IGF-1, CEA and CA125 was 75.33%. Conclusion IGF-1 contributes to early diagnosis of lung cancer and the combined detection of IGF-1, CEA and CA125 could significantly improve the detection rate of lung cancer.