Computed Tomograms of 45 patients with or without lung mass were reviewed to determine the characteristics of the major and minor fissures. Also pulmonary vascular distributions were analyzed to localize each pulmonary lobe. The results were as follows: 1. Each major fissure area was imaged frequently as lucent band, and less frequently dense band. 2. The minor fissure area was imaged frequently as lucent band, and less frequently dense band. 2. The minor fissure area was imaged frequently as lucent zones were as same frequency. 3. Avascular planes without above mentioned lucent zones were also correspond to minor fissure areas. 4. Slices of abascular zones were observated between pulmonary arteries to posterior segment or apico-posterior segment of upper lobe and to superior segment of lower lobe on both lungs.