Introduction: Recent studies have suggested that segmentectomy may be an acceptable alternative treatment to lobectomy for surgical management of smaller lung adenocarcinomas. The objective of this study was to compare survival after lobectomy and segmentectomy among patients with pathological stage IA adenocarcinoma categorized as stage T1b (>0 to <= 20 mm) according to the new eighth edition of the TNM system. Methods: In total, 7989 patients were identified from the Surveillance, Epidemiology, and End Results registry. Propensity scores generated from logistic regression on preoperative characteristics were used to balance the selection bias of undergoing segmentectomy. Overall and lung cancer-specific survival rates of patients undergoing segmentectomy and lobectomy were compared in propensity score-matched groups. Results: Overall, 564 patients (7.1%) underwent segmentectomy. Lobectomy led to better overall and lung cancer specific survival than segmentectomy for the entire cohort (log-rank p < 0.01). After 1:2 propensity score matching, segmentectomy (n = 552) was no longer associated with significantly worse overall survival (5-year survival = 74.45% versus 76.67%, hazard ratio = 1.09, 95% confidence interval: 0.90-1.33) or lung cancer-specific survival (5 -year survival = 83.89% versus 86.11%, hazard ratio = 1.12, 95% confidence interval: 0.86-1.46) compared with lobectomy (n = 1085) after adjustment for age, sex, lymph node quantity, and histological subtype. Similar negative findings were identified when patients were stratified according to sex, age, histological subtype, and number of evaluated lymph nodes. Conclusions: Patients who underwent segmentectomy may have survival outcomes no different than those of some patients who received lobectomy for pathological stage IA adenocarcinomas at least 10 but no larger than 20 mm in size. These results should be further confirmed through prospective randomized trials. (C) 2017 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.