OBJECTIVE Recently, segmentectomy has been considered as an alternative to lobectomy in early peripheral non-small lung cancer (NSCLC); however, controversy has remained regarding the long-term functional advantage after segmentectomy. The aim of this study was to analyze the postoperative lung function after segmentectomy and lobectomy for non-small cell lung cancer. METHODS Patients with p-T1aN0M0 NSCLC who had undergone segmentectomy (n = 37) or lobectomy (n = 33) were retrospectively analyzed. The ratios of postoperative to preoperative forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were defined as the recovery rates. The radiological lung volume and weight were evaluated before and more than 6 months after surgery, and the postoperative values were compared with the predicted values that were calculated from the preoperative values, subtracting the resected lobes or segments. RESULTS The clinical characteristics, including the preoperative lung function showed no significant differences between the groups. No statistical differences were recognized in the trend lines for recovery ratios of FVC and FEV1.0 (P = 0.96 and P = 0.33). The recovery ratios for radiologic lung volume and weight showed no significant differences (P = 0.46 and P = 0.22). The postoperative lung volume and weight were almost the same as the predicted values after segmentectomy, whereas those after lobectomy were significantly higher than the predicted values. CONCLUSIONS No functional advantage for segmentectomy was observed during long-term follow-up, possibly due to compensatory lung growth after lobectomy.