We previously reported a new method of segmentectomy, pulmonary artery-guided segmentectomy as a surgical alternative for small-sized early lung cancer with favorable results, but the follow-up time was too short for definitive conclusion. To examine the efficacy of the segmentectomy, and to determine the appropriate surgical procedure for early lung cancer, we conducted a retrospective follow-up study, and examined the influences of tumor size and preoperative serum tumor marker levels on the prognosis. We reviewed the records of 91 patients who underwent the segmentectomy for pathological T1N0M0 non-small cell lung cancer from 1993 to 2002. In 85 patients, carcinoembryonic antigen, squamous cell carcinoma-related antigen, and a fragment of cytokeratin were measured preoperatively. The overall 5-year survival rate was 83%. Indication (intentional, n=47; compromised, n=44) and tumor size (20mm or less, n=68; 21 to 30 mm, n=23) had no significant impact on survival. The 5-year survival rate for 49 patients with normal tumor marker levels was 93%, and significantly higher than 36 patients with at least one elevated tumor marker level (68%, p<0.01). Median follow-up time of 72.0 months revealed 11 locoregional recurrences. The incidence of locoregional recurrence was significantly higher in the patients with tumors of 21-30 mm, and elevated tumor marker (p<0.01). The follow-up study demonstrated that the segmentectomy could be an acceptable surgical treatment for early lung cancer patients with tumors of 20mm or smaller and normal tumor marker levels.