Among 287 patients underwent pulmonary resection between Mar 1978 and Dec 1989, 49 were proved pathologically to have their primary tumor of 3 cm or less in the greatest dimension. Twelve of these 49 classified to stage III A by the modiastinal lymph node metastasis or stage IV by the pulmonary metastasis. The histologic type of tumor was adenocarcinoma in 10 and squamous cell carcinoma in 2. Mode of surgical treatment consisted of pneumonectomy in 2, lobectomy in 8, segmentectomy or wedge resection in 2, and complete mediastinal lymph node dissection was performed in all but 2. Survival rate in 1, 3, 5 year was 100%, 38.1% and 38.1% in 9 with stage III A disease, and 100%, 100% and 50% in 3 with stage IV disease, respectively, and significant difference was noted in comparison with control group with larger tumor in each stage (p less than 0.05). From these results, we concluded that patients with small primary tumor could expect longer survival after surgical treatment, even if mediastinal lymph node metastasis or pulmonary metastasis was present.