The aim of the study was to evaluate the predictive and prognostic values of elevated serum levels of selected cancer markers (NSE, Cyfra 21-1, CEA, ferritin, free beta-hCG, LDH) in patients with inoperable non-small-cell lung cancer (NSCLC). We investigated a group of 79 patients (49 men and 30 women) with NSCLC. Multivariate regression analysis showed response in patients with NSE > 12.5 ng/ml (p = 0.002), good performance status (p = 0.007) and elderly patients (p = 0.005). However, elevated NSE adversely affected the prognosis. Median survival in patients with NSE < 12.5 ng/ml, 12.5-20.0 ng/ml and > 20.0 ng/ml was 13.3, 11.3 and 6.7 months, respectively (p = 0.004). The negative effect of elevated NSE was independent of the response category. Univariate regression analysis showed that the following factors had a significantly negative effect on the prognosis: performance status, stage IIIB or IV, weight loss of > 10%, NSE > 20 ng/ml, Cyfra 21-1 > 10 ng/ml, CEA > 3 ng/ml, ferritin ratio > 1 and LDH > 480 IU/l. Multivariate analysis showed an independent adverse prognostic effect of stage IIIB or IV and elevated ferritin.