Serum neuron-specific enolase (NSE), tissue polypeptide antigen (TPA), and carcinoembryonic antigen (CEA) were measured in 60 patients with small-cell lung carcinoma (SCLC) and in 94 patients with advanced non-small-cell lung carcinoma (NSCLC) at diagnosis, during induction chemotherapy, and at restaging. At diagnosis, the positivity rates of NSE, TPA, and CEA were 88, 52, and 43% in SCLC, and 20, 62, and 53% in NSCLC, respectively. Serum NSE and TPA levels were significantly higher in extensive than in limited SCLC. TPA and CEA levels were significantly correlated with the extent of NSCLC. NSE and TPA were significantly concordant with the clinical response to initial combination chemotherapy, the former in SCLC, the latter in both SCLC and NSCLC. By discriminant analysis, the presentation levels of the markers were not predictive of response to induction chemotherapy, whereas changes in NSE and TPA levels after the first cycle of chemotherapy were.