Abstract: Objective : To evaluate the application value of diagnosing lung carcinoma by comparing the different expression of carcinoembryonic antigen messenger ribonucleic acid (CEA mRNA) and p53 protein in different type of lung carcinoma. Methods : CEA mRNA was detected by the reverse transcriptase-polymerase chain reaction (RT-PCR) and p53 protein was detected by immunohisto-chemical method. Results : The positive rate of CEA mRNA and p53 protein were 86.7% (26/30) and 46.7%(14/30) in carcinoma tissue, 50.0% (15/30) and 6.7% (2/30) in adjacent tissue, 6.7% (2/30) and 0 in marginal lung tissues, respectively. And the positive rate of them were 90.9% (10/11) and 45.5%(5/11) in squamous cell carcinoma, 90.9% (10/11) and 54.5% (6/11) in adenocarcinoma, 75.0% (6/8)and 37.5% (3/8) in small cell carcinoma. Conclusions : The positive rate of CEA mRNA and p53 protein are higher in lung carcinoma tissue than in adjacent and marginal lung tissue. The positive rate of CEA mRNA is higher than p53 potein in lung carcinoma tissue. CEA mRNA and p53 protein are useful indexes for the diagnosis of lung carcioma.