To determine the clinicopathologic characteristics of peripheral non-small-cell carcinomas, the cases of 337 patients undergoing major pulmonary resection with complete lymphadenectomy were retrospectively reviewed with regard to lymph node involvement, recurrence, and prognosis. All of the tumors were 3.0 cm or less in diameter and were categorized as T1 (318 patients) or T2 (19). Eighty-eight patients (26.1%) had lymph node involvement: 32 (9.5%) at N1 nodes, 55 (16.3%) at N2 nodes, and 1 (0.3%) at N3 nodes. Although the prevalence of lymph node involvement did not differ significantly with tumor histologic type, it was quite low in squamous cell carcinomas 2.0 cm or less in diameter. Of the 56 N2/3 metastases, 14 (25%) occurred in a "skipping" manner, and all but one had a nonsquamous histologic makeup. Of the 213 patients with a follow-up period of 5 years or more, 59 patients (27.7%) showed cancer recurrence. This occurred at a distant site in 67.8% of the cases. Five-year survival rates based on nodal status were 91.9% (NO), 61.8% (N1), 44.5% (N2), and 0% (N3). Because of the relatively high prevalence of lymph node involvement, complete hilar/mediastinal lymphadenectomy should be routinely done regardless of tumor histologic type and size, as long as patients are at good risk. However, in squamous cell histologic types, mediastinal lymphadenectomy might be dispensable if the tumor is less than 2.0 cm in diameter, or if the hilar node is proved to be tumor-free on pathologic examination of the frozen section during operation. Although video-assisted major pulmonary resection currently has limited application, this new technique may represent a surgical option in resection without complete lymphadenectomy.