Objective To investigatethe significance of serum carbohydrate antigen (CA) 125,car cinoembryonic antigen (CEA),cytokeratin 19 fragment (CYFRA21-1),neuron-specific enolase (NSE),and squamous cell carcinoma antigen (SCCA) in the diagnosis of bone metastasis from lung cancer.Methods A total of 222 patients,including 91 lung cancer patients with bone metastasis (49 males,42 females,average age (60.07± 10.60) years;group A),75 lung cancerpatientswithout bone metastasis (57 males,18 females,average age (62.20± 12.63) years;group B),56 patients with benign lung diseases (34 males,22 females,average age (61.45± 10.66) years;group C) were recruited from January 2015 to January 2016.The electrochemiluminescence was applied to detect serum levels of CA125,CEA,CYFRA21-1,NSE and SCCA.Kruskal-Wallis,Wilcoxon rank sum test,x2 test and receiver operating characteristic (ROC) curve analysis were used to analyze data.Results The levels of serum CA125,CEA,CYFRA21-1,NSE in group A were higher than those in group B and C (H values:13.45-44.96,all P＜0.05);while SCCA was not significantly different among the 3 groups (H=2.56,P＞0.05).The areas under ROC curves for CA125,CEA,CYFRA21-1,NSE,SCCA were 0.667,0.702,0.602,0.664,0.440,respectively.The positive rate of serum NSE in small cell lung cancer (SCLC) patients was higher than that in non-small-cell lung cancer (NSCLC) patients (17/18 vs 32.88％ (24/73);x2=22.11,P＜0.05);CEA was highly expressed in adenocarcinoma,and SCCA was highly expressed in squamous cell carcinoma.Patients with grade Ⅲ+ Ⅳ metas tasis (n =52) had higher levels of CA 125,CEA,NSE compared to patients with Ⅰ + Ⅱ metastasis (n =39;z values:from-2.54 to-0.32,all P＜0.05).The sensitivity of combined detection of 5 tumor markers was 97.80％ (89/91),which was significantly higher than that of single tumor marker (x2 values:35.46-138.23,all P＜0.05).Conclusion Serum levels of CA125,CEA,CYFRA21-1,NSE and SCCA play a role in the diagnosis of bone metastasis from lung cancer,and the combined detection of the 5 tumor markers contribute to the early detection of bone metastases.