The results of computed tomography (CT) staging and surgical data have been compared to assess the former in diagnosing localized lung cancer. The study included 79 patients with locally advanced non-small cell lung cancer who had been treated by surgery. Local invasion was adequately diagnosed by CT in 67 (84.8%) and primary tumor stage--51.9%; overdiagnosis--15.2% and underdiagnosis--32.9%. The CT and final diagnosis findings on lymphogenous dissemination matched in 64.6%; overdiagnosis--16.5% and underdiagnosis--18.9%. Sensitivity, specificity and diagnostic accuracy in identifying stage T3 and T4 tumors were 62.3, 65.4 and 63.3%, respectively; lymphogenous dissemination--76.9, 64.9 and 74.7%, respectively.