Abstract OBJECTIVES The purpose of this study was to assess the quality of video-assisted cervical mediastinoscopy (VACM) in the staging of non-small-cell lung cancer (NSCLC) at the Antwerp University Hospital with a focus on test effectiveness indicators, morbidity and unforeseen pN2 results. METHODS All consecutive VACM workups of cases of NSCLC performed between January 2010 and December 2015 were included to assess overall test quality and effectiveness. Quality assurance was performed in accordance with the recommendations of the European Society of Gastrointestinal Endoscopy and European Society of Thoracic Surgeons (ESTS) where appropriate. RESULTS A total of 168 video-assisted cervical mediastinoscopies were included. A total of 91.7% of the procedures were performed in accordance with the ESTS guideline. An unforeseen pN2 staging was identified in 10 anatomical lung resections (8.6%). Statistical analysis showed no significant association between VACM performed in accordance with the ESTS guideline and the presence of pN2 positive lymph nodes [χ2 (1) = 0.61; P = 0.57] and no association between VACM performed in accordance with the ESTS guideline and overall futile thoracotomy [χ2 (1) = 0.76; P = 0.50]. Calculations revealed a sensitivity of 81.8 [95% confidence interval (CI) 69.1–90.9], specificity of 100%, positive predictive value of 100%, negative predictive value of 91.9% (95% CI 86.6–95.2) and diagnostic accuracy of 94.1% (95% CI 89.33–97.11). CONCLUSIONS Overall, 91.7% of the VACM were performed in accordance with the ESTS guideline. This process resulted in a sensitivity of 81.8%, a negative predictive value of 91.9% and an unforeseen pN2 rate of 8.6%.