['Pulmonary fissure differs among patients, but the relationship between pulmonary fissure development and survival in patients with resected lung adenocarcinoma has not been evaluated. In this study, we analyzed the effect of fissure development on prognosis in patients with stage I lung adenocarcinoma.', 'From January 2009 to December 2012, data, including pulmonary fissure development, were collected prospectively for all lung cancer, and this was a retrospective study of prospectively collected data. In total, 297 patients who had undergone a lobectomy and had pathologic stage I adenocarcinoma were analyzed. Patients were categorized into two groups based on fissure sum average (FSA) fissure development scores. Group A patients ranged from complete to 30% incomplete (0\u2009≤\u2009FSA\u2009≤\u20091) while in Group B patients development was more than 30% incomplete (1\u2009<\u2009FSA\u2009≤\u20093).', 'In univariate analysis, Group B had poorer overall 5 year survival than did Group A (83.1% vs. 96.5%, P\u2009=\u20090.015). Multivariate analysis revealed that the level of fissure development was a significant prognostic factor for overall survival (HR\u2009=\u20093.905, CI\u2009=\u20091.168-13.057, P\u2009=\u20090.027).'] Is pulmonary fissure development a prognostic factor for patients with resected stage I lung adenocarcinoma?