The recent 5-year survival rate of patients with lung cancer who underwent resection is significantly higher than that in the previous decade. The main reason for the improved survival rate seems to be due to more accurate staging, however, we cannot detect micrometastases so that distant relapses in many patients occur after operation. In order to control micrometastases, various kinds of surgical adjuvant therapy have been studied. In an attempt to improve resectability rate and survival in patients with locally advanced disease of non-small cell lung cancer, we initiated a pilot study of neoadjuvant (preoperative) therapy. Most of the 31 patients who were entered into the study clinically showed enlarged mediastinal lymph nodes, with or without direct invasion of the primary tumors to mediastinal organs. The response rate of the treatment was 64.5%. Complete resection of the tumor was performed in 14 of 31 (45%) patients and exploratory thoracotomy was done in one patient. Postoperative complications occurred in 6 of those 15 patients who underwent thoracotomy. Three patients suffered from severe complications such as empyema, pulmonary edema or respiratory failure, but recovered eventually. At present, of 15 patients who underwent operation, 9 are alive and free from disease, 2 are alive with relapse and 4 died of relapses. The median survival time was 11.5 and 19 months in non-resected cases and all cases, respectively. Although we cannot draw a conclusion because of the short observation time, we consider that neoadjuvant therapy is worthy of studying.