The usefulness of serum tumor markers in lung cancer is not well defined. Objective: The aim of this study is to examine the correlation between serum tumor markers and tumor extension and its prognostic value. Patients and method: From February 1995 to September 1997, 103 patients with non-small cell lung carcinoma were evaluated at the Department of Thoracic Surgery. Serum levels of CEA, CYFRA21.1, CA15.3, CA19.9, CA72.4, and NSE were determined before treatment. Results: The serum level of CYFRA21.1 was the most frequent elevated tumor marker (55%). Patients with advanced tumor had higher mean serum level of CEA (90.8 ng/ml), CYFRA21.1 (20.3 ng/ml) and CA15.3 (56.5%) than those with localized carcinoma, respectively 10.2 ng/ml, 12.6 ng/ml and 22.2 ng/ml. Considering all serum tumor markers evaluated in this study, only patients with elevated CEA had greater chance (5.6) of presenting with advanced non-small lung carcinoma than patients with normal CEA. Overall survival was influenced by performance status (p = 0.001), tumor extension (p = 0.006), elevated serum level of CEA (p = 0.043), more than two elevated serum tumor markers (p < 0.001), and type of treatment (p < 0.001). The prognostic value of anatomical tumor extension reached the limit of significance (p = 0.052); however, two or more elevated serum tumor markers and type of treatment had independent prognostic value (respectively, p = 0.035 and p = 0.005). Conclusion: None of these serum tumor markers had clinical value in the management of NSCLC patients.