Background Neuron-specific enolase (NSE) is the most sensitive tumour marker for small-cell lung carcinoma (SCLC) at the time of diagnosis. The main purpose of this study was to review the usefulness of serum NSE level as a prognostic factor in patients with SCLC and to determine the correlation between the NSE level and the stage of disease and response to chemotherapy. Methods In this prospective study, patients with SCLC were evaluated for response to chemotherapy, survival without disease progression, and overall survival. The end point was designated at patient death due to SCLC. NSE assays were performed before and after completion of chemotherapy. Results Sixty-five patients were included in study. NSE levels were significantly higher in patients who died of SCLC. The pre-treatment NSE levels in patients who responded to treatment were significantly lower. The post-treatment NSE levels were not significantly correlated with response to chemotherapy, progression-free survival, overall survival, and prognosis of patients. Change in the NSE level between the pre- and post-treatment periods was not significantly correlated with response to treatment, progression-free survival, and overall survival. Conclusions NSE levels might not be related with the stage of the disease. However, a low pre-treatment NSE level might be used in predicting good response to chemotherapy in patients with SCLC. The post-treatment serum NSE levels and the rate of change between pre- and post-treatment serum levels of NSE were not related with response to chemotherapy, progression-free survival, and overall survival.