Purpose: The purpose of this study was to clearly define the subsuperior bronchus (B*), and to reestablish the bronchial anatomy of the right lower lobe (RLL) by thorough evaluation of the atypical bronchi in the RLL. Methods: Chest computerized tomographic (CT) scans of 500 consecutive patients with normal CT findings were evaluated, retrospectively. All CT scans were obtained from 64 slice scanners, and all CT images were reconstructed by 1mm thickness and 1mm interval. According to the running direction and shape, atypical bronchi in the RLL were classified as lateral (Lat), posterolateral (PL), posterior (Post), Lat+PL and PL+Post. Atypical bronchi in the stem of basal segmental bronchi (BSB) were classified as B* which ran posteriorly or posterolaterally and para-lateral bronchus (Para-B8) which ran laterally. All images were interpreted by two chest radiologists by consensus, and following parameters were evaluated; 1) the frequency and type of atypical bronchi arising from each BSBs and from the stem bronchi, 2) the relationship between atypical bronchi arising from the BSBs and those from the stem bronchi. Results: In the level of BSB, Lat (98.8%), PL (94.0%) and Post (100%) arose from B8, B9 and B10, respectively. All Lat+PL arose from B8 or B9, and all PL+Post arose from B9 or B10. Also, when they arose from the one of a pair of BSBs, no atypical bronchi arose from the another (Lat+PL: 93.8%, PL+Post: 88.0%). The frequency of B* and Para-B8 were 27.2% and 11.8%, respectively. In 98.6%, B* and Para-B8 arose from the stem spreading the connatural BSBs of the atypical bronchi which formed B* or Para-B8. In 82.6% of the cases with B* or Para-B8, no atypical bronchi were identified at BSBs arising from the stem bronchus. Conclusion: Lat, PL and Post should be considered as the first subsegmental bronchus of B8, B9 and B10, respectively. The term of B* and Para-B8 should be restrictively used when atypical bronchi were identified at the stem bronchus. Lat+PL and PL+Post in the level of BSB may be the results of the fusion of atypical bronchi during downward migration, B* and Para-B8 in the stem may be the results of the arrest of downward migration of atypical bronchi. This knowledge is useful for application of the segmentectomy of the RLL.