We surgically treated 185 patients with non-small cell lung cancer who were 70 years old or older. The operative mortality rate was 3%, and the 5-year survival rate was 48%. The mortality and prognosis were similar to those in younger patients. The number of elderly patients who smoked heavily or who had ventilatory defects was high, but the incidence of pneumonectomy was low. There were no differences based on age in regard to histological type, TNM classification, and curability. Pulmonary complications occurred in 21% of the elderly patients and were correlated with preoperative pulmonary function and smoking habits. When the elderly are to undergo elective pulmonary resection for lung cancer, the preoperative evaluation of pulmonary function should be thorough, and both preoperative and postoperative physical therapy should be given. If postoperative pulmonary function is predicted to be less than 0.8 L/m2 of vital capacity and 0.6 L/m2 of forced expiratory volume in 1 second, a limited resection or nonsurgical therapy should be considered.