Recently, the greater utilization of computed tomography (CT) has led to an increasing proportion of small-sized stage I A lung cancer in less than 1 cm in diameter. However, a treatment strategy for these small-sized lung cancers has not yet been defined. The aim of this study was to investigate surgical outcomes regarding these lung cancers. A total of 123 patients who underwent complete surgical resection for lung cancer in less than 1 cm between January 1995 and March 2010 were retrospectively evaluated. The 123 study subjects consisted of 54 male and 69 female patients. The mean age was 64.0 (43~82) years. The mean tumor size was 0.9( 0.3~1.0) cm. In this study, 70 patients underwent lobectomy (56.9%). Segmentectomy and wedge resection were underwent 23( 18.7%) and 30 patients( 24.4%), respectively. The 3-, 5- and 10-year survival rates were 95.7, 92.3 and 85.7%, respectively, after the operation for lung cancer in less than 1 cm. There were no significant difference between sublobar resection and lobectomy. However, 2 patients( 1.6%) had recurrent cancer and 7 patients (5.7%) had lymph node metastasis. We suggested surgical procedure for patients with lung cancers in less than 1 cm should be selected with the greatest care, because recurrent cancer and lymph node metastasis can occur in patients.