Numerous studies have been performed to determine diagnostic or prognostic utility of tumor markers in patients with lung cancer. The aim of the study was to evaluate the diagnostic usefulness of the tumor markers CA 125, CEA and CYFRA 21-1 in bronchoalveolar lavage fluid (BALF) in patients with non-small cell lung cancer (NSCLC). BAL was performed in 13 patients with NSCLC during diagnostic bronchofibroscopy. The control group consisted of 12 patients with sarcoidosis and 13 healthy volunteers. Tumor markers were determined in BALF supernatants using electrochemiluminescence technique (Elecsys 1010, Roche). To determine optimal cut-off values of tumor markers in BALF ROC curve was used. CEA and CA 125 concentration in BALF were significantly higher in NSCLC patients than in healthy volunteers and patients with sarcoidosis. CYFRA 21-1 in BALF was higher in NSCLC patients than in healthy volunteers, but no significant difference was found between NSCLC and sarcoidosis patients. The cut-off values of BALF concentration of CA 125, CEA and CYFRA 21-1 were 95 IU/mL, 3 ng/ml and 3 ng/ml, respectively. The sensitivity and specificity of CEA and CA 125 in BALF were 100%, 84% and 92%, 80%, respectively. In conclusion, we suggest that among the chosen markers, determination of CEA in BALF is the most useful in diagnosis of NSCLC. It may be a complementary method in diagnosing of patients in whom tumor cannot be visualized by bronchofibroscopy. These results need confirmation in larger groups of patients.