Fifty-seven patients with small cell lung cancer were operated on at the National Cancer Center Hospital, Tokyo, between 1962 and 1986. Twenty-seven patients had oat cell type and thirty had intermediate cell type. The five-year survival rate of patients who were treated before 1979 (the first term) was only 11%, whereas the rate for patients treated after 1980 (the latter term) was 53%. No patient with oat cell type small cell lung cancer, treated in the first term, survived for three years after the operation. However, four patients with oat cell type lung cancer, treated in the latter term, survived for five years or more after surgery. The five-year survival rate of the patients with oat cell type lung cancer, who were treated after 1980, was 64%. The five-year survival rates for patients with intermediate cell type were 20% in the first term and 41% in the latter term. We have introduced CT and echography for the preoperative evaluation of patients and also perioperative intensive chemotherapy. Improvement of preoperative evaluation and intensive chemotherapy have yielded good results.