A comparative study on the effect of neoadjuvant chemotherapy was performed for small cell lung cancer, by radiographic and histopathological examinations. Four patients with small cell lung cancer were preoperatively treated with the combination of cyclophosphamide, doxorubicin, vincristine, nimustine, cisplatin and vindesine, for 2 to 3 cycles. The clinical responses to the neoadjuvant chemotherapy included 2 complete, one partial response and one no change. All four patients underwent a planned operation. Based on microscopical evidence, the two complete responders had a residual tumor in the resected specimens. One was tumor-free after 28 months, while the other succumbed to operation-related death at 2 months. The remaining two inadequate responders relapsed and died shortly following operation. We believe a clinically complete responder should be differentiated from a 'true' complete responder by histopathological examination.