BACKGROUND We have developed a new bronchoscopy system with two independent lenses at the tip of the device. This enables measurement of object size using the principle of triangulation. This study was performed to assess the accuracy of this system. METHODS The accuracy of the bronchoscopy system was confirmed by measuring the diameters of four plastic tubes and 36 airway calibres in 12 surgical patients under general anaesthesia. The measured diameters of the tubes and airway tracts were compared with the manufactured diameters of tubes and those measured by high-resolution computed tomography (HRCT)-based virtual bronchoscopy, respectively. RESULTS Using the new bronchoscope system, tube diameters, 9, 12, 15, and 19 mm, were measured as 9.9 (0.7), 12.8 (1.4), 16.3 (1.6), and 20.1 (2.0) mm, respectively. Airway calibres obtained by a stereovision bronchoscopy and HRCT-based virtual bronchoscopy were 8.66 (4.31) and 9.38 (5.09) mm, respectively. There is a significant correlation between airway calibres with the two measurement methods (r=0.975, P<0.01). CONCLUSIONS We have confirmed that this new bronchoscopy system could provide relatively accurate quantitative data. This new system may be useful in the clinic to measure airway dimension and lesion sizes such as tumours.