VB images could be produced to a median of the sixth- (third- to ninth-) order bronchi. Ultrathin bronchoscopy could be performed without complications in all subjects, and the median examination time was 24.9 min (range, 11.6 to 58.2 min). The median time of the use of the virtual navigation system was 2.6 min (range, 1.1 to 8.3 min). The bronchial branchings on VB images were in good accordance with the actual branchings. For 28 lesions, the ultrathin bronchoscope could be advanced under direct vision into the bronchus for which VB images could be produced. For eight lesions, the ultrathin bronchoscope could be advanced only one to two branchings before the bronchus for which VB images could be produced, although the bronchoscope remained on the planned route. Therefore, for 36 lesions, the ultrathin bronchoscope could be guided through the planned bronchial route using this system under direct vision. For the other two lesions, since the branching on VB images differed from the actual branching, the bronchoscope was advanced into a wrong bronchus. In these cases, the bronchoscope was guided to the planned route using CT fluoroscopy. The biopsy forceps could be advanced to the lesion in 33 of the 38 lesions (86.8%), and diagnosis could be made for 31 of the 33 lesions. Lung cancer was diagnosed in 17 lesions (adenocarcinoma, n = 14; small cell carcinoma, n = 1; squamous cell carcinoma, n = 1; and non-small cell carcinoma, n = 1); metastasis of ovarian cancer in 1 lesion; tuberculosis in 1 lesion; nontuberculous mycobacterial disease in 2 lesions; and inflammation in 10 lesions. The lesions determined to be inflammation decreased in size or disappeared during the subsequent observation period, which was consistent with the clinical characteristics of inflammation. Of the two other lesions in which a diagnosis was not made, one lesion showed no malignant findings and hamartoma was diagnosed by operation, and the other lesion was suggested to contain a few malignant cells by cytodiagnosis but a diagnosis could not be made by histologic examination, and lung cancer (adenocarcinoma) was subsequently diagnosed by surgery. The five lesions to which the forceps could not be advanced showed no bronchus involvement by the lesion on TSCT images. For these lesions, the ultrathin bronchoscope could be guided to the target bronchus that was the closest to the lesion, but the forceps could not be guided to the lesion. Of the five lesions, lung cancer was diagnosed (large cell carcinoma) in one lesion by surgery, lung cancer (adenocarcinoma) by conventional bronchoscopy performed as re-examination in one lesion, metastatic lung tumor (metastasis of colorectal cancer) based on the clinical course in one lesion, and inflammation based on the clinical course in one lesion; and the other lesion is still under observation without diagnosis. The diagnosis rate of this procedure was 81.6% for the 38 lesions examined by ultrathin bronchoscopy: 80.8% for 26 lesions ≤ 20 mm in size, and 83.3% for 12 lesions > 20 mm. In the 28 lesions for which the involved bronchus was clear, the forceps arrival rate was 96.4% and the diagnosis rate was 89.3%. In the 10 lesions for which the involved bronchus was unclear, the forceps arrival rate was 60.0% and the diagnosis rate was 50.0%. For the 37 lesions that could be finally diagnosed, the sensitivity, specificity, negative predictive value, positive predictive value, and accuracy for malignant disease were 81.8%, 100%, 78.9%, 100%, and 89.2%, respectively.