Abstract: Objective:To investigate the value of the combined detection of carcinoembryonic antigen(CEA),cytokeratin 19 fragment(CYFRA21-1),neuron specific enolase(NSE) and carcinoembryonic antigen 72-4(CA724) in the diagnosis of lung cancer.Methods:The serum levels of CEA,CYFRA21-1,NSE,CA724 in 56 cases with lung cancer(24 cases with adenocarcinoma,20 cases with squamous cell carinoma and 24 cases with small cell carcinoma),34 cases with benign pulmonary diseases and 30 healthy people were detected and analysed using electrochemiluminescence.Results:The differences of the serum levels of CEA,CYFRA21-1,NSE and CA724 in five groups were statistical significant(P0.01).The levels of CEA in adenocarcinoma group,CYFRA21-1 in squamous cell carcinoma group and NSE in small cell carcinoma group were significantly higher than those in other groups(P0.01).The level of CA724 in adenocarcinoma group was significantly higher than that in control group and benign disease group(P0.01).The positive rates of CEA in adenocarcinoma group,CYFRA21-1 in squamous cell carcinoma group,NSE in small cell carcinoma group and CA724 in adenocarcinoma group were higher than those in control group and benign disease group(P0.05 to P0.01).The specificities and sensitivities of the individual detection of 4 kinds of markers were 88.9% to 94.4% and 28.6% to 41.1%,respectively.The specificity and sensitivity of the combined detection of 4 kinds of markers decreased(83.3%) and increased(87.5%),respectively.Conclusions:There is certain correlation between the serum levels of CEA,CYFRA21-1,NSE and CA724 and the pathological type of lung cancer,the combined detection of which can improve the postive detection rate of lung cancer.