Ten patients with lung cancer complicated by severe pulmonary emphysema, underwent lung reduction surgery between 1995 and 1997. Patients meeting the following criteria were defined as having severe pulmonary emphysema: (1) forced expiratory volume in 1 s (FEV1%) of < 55% and (2) characteristic, severe findings of emphysema in chest x-rays and chest computed tomography scans. 9 men and 1 woman (mean age: 70.8; range: 59-78 years), were all smokers (smoking index: 500-2450). Preoperative lung function showed an average percent vital capacity of 87.8% (range: 67-108%) and an average FEV1% of 35.9% (range: 27-54%). The histological types of lung cancer were squamous cell carcinoma (4 patients), adenocarcinoma (5 patients), and large cell carcinoma (1 patient). Four patients were in clinical stage IA, 3 in stage IB, and 1 each was in stages IIA, IIIA, and IIIB. Lobectomy was conducted in 3 cases and partial resection in the remaining 7. Five of the 10 patients underwent thoracoscopic resection. After surgery, patients died one at 2 months and the other at 17; 3 survived but 3 suffered cancer recurred; and 5 patients without recurrence. In complications, bronchial air leakage requiring postoperative treatment. Postoperative lung function showed an average percent vital capacity of 71.4% (range: 41-90%) and an average FEV1% of 41.3% (range: 28-61%). We found an important relationship between the location of the perfusion defect (target area) in pulmonary perfusion scintigram in relation to the lung cancer site and postoperative improvement of lung function. One patient with lung cancer associated with severe respiratory obstruction underwent lobectomy after confirmation of the perfusion defect by pulmonary perfusion scintigram. Postoperative FEV1% in this patient was restored to the preoperative level. In general, partial thoracoscopic resection was effective in patients with early-stage lung cancer.