The levels of carcinoembryonic antigen (CEA), squamous cell associated antigen (SCC-Ag) and carbohydrate antigenic determinant 19-9 (CA 19-9) were assessed in 70 patients with non-small cell lung cancer (NSCLC) and in 20 patients with non-malignant lung diseases. Increased levels of CEA and CA 19-9 were observed in 55.7 and 44.2%, respectively, mostly in patients with adenocarcinoma (adeno C; 69.5 and 56.5%). Increased levels of SCC-Ag were observed in 45.7%, first in patients with squamous cell carcinoma (68.6%). Serum CEA, CA 19-9 and SCC-Ag levels were correlated with the postoperative, pathological stage of disease. Positive CEA levels in patients with adeno C were present in 50% of stage 1, 66.6% of stage 2 and 88.8% of stage 3; positive CA 19-9 levels in patients with adeno C were present in 30% of stage 1, 66.6% of stage 2 and 80% of stage 3; positive SCC-Ag levels were present in patients with squamous LC in 50% of stage 1, 83.3% of stage 2 and 73.7% of stage 3. The study proved that preoperative CEA, SCC-Ag and CA 19-9 determination have been shown to be of prognostic value in patients with NSCLC. A high preoperative antigen value suggests a worse prognosis than a lower value.