BACKGROUND: Prospective assessment of accuracy and safety of video-mediastinoscopy (VMS) in patients without pretreatment and those after induction therapy for potentially operable non-small cell lung cancer. METHODS: Between 1996 and 1999, 219 patients underwent VMS at our institution: 195 patients without pretreatment and 24 after completion of induction therapy. Mediastinal lymph nodes were dissected and biopsied according to the American Thoracic Society (ATS) lymph node mapping system using a video-assisted approach. The accuracy of VMS was assessed for each patient according to the results obtained from mediastinal lymph node dissection (MLND) performed during lung resection. RESULTS: Video-mediastinoscopy in patients without pretreatment revealed a sensitivity, specificity, and accuracy as compared with MLND of 87%, 100%, and 95.6%, respectively, and a procedure-related complication rate of 4% (8/195 patients). Video-mediastinoscopy in patients after induction therapy revealed a sensitivity, specificity, and accuracy of 81%, 100%, and 91% as compared with MLND, without apparent complications. CONCLUSIONS: Video-mediastinoscopy performed after induction therapy for non-small cell lung cancer is as accurate as mediastinoscopy in patients without pretreatment and did not confer additional morbidity.