BACKGROUND The preoperative staging of lung cancer can be problematical when we attempt to evaluate T factor (T2-T3 versus T4) and N factor (N0 versus N1-N2). In some cases, radiology tests (CT scan, magnetic resonance imaging) cannot entirely dispel the possibility that the mediastinal structures have been infiltrated. N factor is evaluated mainly by dimensional criteria. However, mediastinoscopy and mediastinotomy do not allow the full exploration of all mediastinal mode stations. METHODS Starting in 1995, we submitted 10 consecutive patients to videothoracoscopic operative staging with ultrasound color Doppler (VOS-USCD). In five cases, preoperative staging showed possible infiltration of the pulmonary artery (T4). In nine cases, we found involvement of the mediastinal nodes, seven patients were N2, and two were N3. Videothoracoscopy was performed under general anesthesia using a double-lumen endotracheal tube. The videothoracoscope and sonographic probe were inserted via three thoracoports placed in the axillary triangle. RESULTS Following the results of VOS-USCD, the staging and subsequently the therapeutic program were modified in seven of 10 cases (70%). CONCLUSIONS Our preliminary experience indicates that VOS-USCD should be applied to the diagnosis of patients in stage IIIA (N2) and that it is particularly valuable for patients in stage IIIB.