Background. Bf-NAVI^[○!R] is a virtual bronchoscopic navigation (VBN) system commonly used in Japan, which is useful for the diagnosis of peripheral lung lesions by bronchoscopy. The recommended CT slice thickness for Bf-NAVI is 1.0 mm and less to generate accurate virtual images. However, the optimal slice thickness still remains unclear. Subjects and Methods. We retrospectively analyzed the medical records of patients with peripheral lung lesions who underwent bronchoscopy from August to October 2013 at our institution. We created 2 types of DICOM files with different slice thicknesses (0.5 mm and 1.0 mm) from their CT images and generated virtual images using Bf-NAVI and performed comparative analysis between them. Results. Thirty patients were included in this study and the median lesion size was 23.2 mm. The time required to generate virtual images was significantly longer among 0.5-mm-slice thickness than 1.0-mm (median, 13.0 min vs. 8.3 min, p<0.01). We could visualize more distal bronchi using 0.5-mm-slices in 20 patients (67%) but there were no statistically significant differences in bronchial generation of virtual images (median, 5 vs. 4, p=0.16). The number of virtual images along the entire pathway to a target lesion was greater using 0.5-mm-slices (11 patients [37%] vs. 5 patients [17%], p<0.01). Conclusions. Although CT images using 0.5-mm-slice thickness require a longer time to construct virtual images, they are useful to generate more distal bronchi in virtual images.