Objective To investigate whether HSP90α could be a sensitive and specific serum biomarker for the diagnosis and progression of lung cancer. Methods In the present study, different secretomic analy-ses on the two human lung adenocarcinoma cell lines CL1-0 and CL1-5 with low and high metastatic poten-tial, respectively, were performed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and ma-trix-assisted laser desorption/ionization time-of-flight mass spectrometry. The candidate biomarker was con-firmed by Western blotting, and was further analyzed in 224 serum samples including 141 lung cancer, 37 benign pulmonary diseases, as well as 46 healthy individuals using ELISA assay. Results HSP90α was sig-nificantly upregulated in the CM of CL1-5 cells. It was found that the levels of HSP90α were specifically ele-vated in the sera of non-small cell lung cancer compared with other groups. At the cut-off point 0.535 on the receiver operating oharacteristie curve, HSP90α could comparatively discriminate lung cancer from benign lung disease and healthy control groups with sensitivity of 0. 817, specificity 0. 919 and total accuracy 80. 14%. Conclusion HSP90α may be a potential useful serum biomarker for discriminating lung cancer from benign lung diseases and healthy individuals and staging of non-small cell lung cancer.