To assess the role of pneumonectomy for lung cancer and the factors affecting the prognosis, 107 patients who had undergone pneumonectomy for non-small cell lung cancer (NSCLC) between January, 1985 and March, 1996, were analyzed. They included 81 squamous cell carcinoma, 22 adenocarcinoma, 3 large cell carcinoma, and one adenosquamous cell carcinoma, with 8 patients in post-operative stage I, 15 in stage II, 51 in stage IIIA, and 33 in stage IIIB of the disease. The 5-year survival rate was 54.7% in stages I + II, 38.0% in stage IIIA, and <4% in stage IIIB. In stages I-IIIA, the patients with squamous cell carcinoma showed a significantly better prognosis than those with adenocarcinoma (50.6 vs. 0%, p < 0.01). The prognosis was also better, but not statistically significant, for patients with central type compared with those with peripheral type in both all histologic types (58.0 vs. 8.4%) and only squamous cell type (59.3 vs. 18.8%). A better prognosis observed in squamous histologic type or central type seemed to be related to a better N factor. Pneumonectomy remains the treatment of choice for lung cancer, but seems not to be justified for patients with stage IIIB due to their poor prognosis.