The aim of this study was to evaluate the diagnostic value of carcinoembryonic antigen (CEA) in non-small cell lung cancer (NSCLC). A prospective study included 187 patients with NSCLC. Results: Se and Sp of CEA is 66 percent and 98 percent in diagnostic NSCLC. Serum medial CEA showed significantly higher levels in the cancer group than in control group (29,27 ng/ml vs 1,33 ng/ml). The levels of CEA is increasing by stages of NSCLC and with the highest in adenocarcinoma lung cancer patients (47,50 ng/ml).