We attempted to determine the smallest size of nodule that could be accurately diagnosed by fluoroscopic fiberoptic bronchoscopy (FFB) and computed tomography (CT) guided trans-corporeal biopsy (CTGB) procedures. Parenchymal lesions (n=1483) detected using chest roentgenography were investigated in the present study, and the diagnostic capabilities of FFB and CTGB were determined based on receiver-operating characteristic curves. A total of 990 nodules (67%) were diagnosed using FFB, while 58 (4%) were diagnosed with CTGB, 339 (23%) by surgery, and 100 (6%) by other methods. The area under the curve (AUC) was 0.74 (0.72<95% CI <0.77) in FFB cases and 0.95 (0.92<95% CI <0.98) in CTGB cases. FFB was found capable of diagnosing nodules with sizes between 0 and 1.0 cm, 1.0 and 1.5 cm, 1.5 and 2.0 cm, and more than 2.0 cm at ratios of 0/58 (0%), 19/115 (16%), 59/141 (35%), and 1072/1173 (97%), respectively (P<0.0001). The diagnostic ability of CTGB for nodules categorized in the same manner was 0/25 (0%), 2/29 (7%), 5/24 (21%), and 53/63 (84%), respectively (P<0.0001). For SPNs smaller than 1.5 cm in diameter, both FFB and CTGB showed a low diagnostic sensitivity.