PURPOSE: To evaluate further the right minor and major fissure on thin-section narrow-interval CT scans with particular emphases on orientation, degree of completeness. MATERIALS AND METHODS: Thin section CT scans from 10 mm distal to carina to the proximal basal segmental bronchus were obtained at 5 mm invervals in 50 consectutive subjects. Orientation, degree of completeness, and the relationship of the minor and major fissure on thin-section CTscans were analyzed. RESULTS: Four principal types of the minor fissure could be identified according to the highest point of the upper surface of the middle lobe. At bronchus intermedius level, the major fissure appeared with its medial end anterior to lateral end in 45 subjects. The minor fissure was complete in only 10 subjects (20%). Completely absent minor fissure was noted in four subjects (8%). The major fissure was incomplete in 17 subjects (34%) at bronchus intermedius level. the minor and major fissure intersected each other in only 27 subjects (54%). The hig best point of intersection was variable. CONCLUSION: There are much more variations in the fissural complex in our study than in previous reports and these variations can be visualized well on thin-section CTscans.