Guidelines for invasive mediastinal nodal staging in resectable NSCLC have changed over the years. The aims of this study were to describe trends in invasive staging and unforeseen N2 (uN2) and to assess a potential effect on overall survival (OS).A nationwide Dutch cohort study included all clinical stage IA-IIIB NSCLC patients primarily treated by surgical resection between 2005 and 2017 (n=22 555). We assessed trends in invasive nodal staging (mediastinoscopy, 2005-2017; endosonography, 2011-2017), uN2 and OS and compared outcomes in the entire group and in cN1-3 patients with or without invasive staging.An overall increase in invasive nodal staging from 26% in 2005 to 40% in 2017 was found (p<0.01). Endosonography increased from 19% in 2011 to 32% in 2017 (p<0.01), while mediastinoscopy decreased from 24% in 2011 to 21% in 2017 (p=0.08). Despite these changes uN2 was stable over the years at 8.7%. Five-year OS rate was 41% for pN1 compared to 37% in single node uN2 (p=0.18) and 26% with more than one node uN2 (p<0.01). Five-year OS rate of patients with cN1-3 with invasive staging was 44% versus 39% in patients without invasive staging (p=0.12).A significant increase in invasive mediastinal nodal staging in patients with resectable NSCLC was found between 2011 and 2017 in the Netherlands. Increasing use of less invasive endosonography prior to (or substituting) surgical staging did not lead to more cases of uN2. Performance of invasive staging indicated a possible overall survival benefit in patients with cN1-3 disease.This project did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.