The distribution of centrilobular emphysematous lesions in the transverse plane was studied with high-resolution CT (HRCT) images of inflated and fixed lungs obtained from 49 patients with centrilobular emphysema (CLE). The transaxial distribution of low attenuation areas (LAA) was assessed quantitatively on HRCT images obtained from 21 patients. LAA in the outer layer accounted for a significantly lower ratio of the lung parenchyma than did those in the inner layer. Macroscopic analysis of 31 lobes obtained from 28 patients with CLE was done by point counting. The inner layer had many more LAA than the outer layer. Bronchiolar lesions were examined under the microscope for their relation to the observed variations in distribution in CLE. No significant differences were found in the bronchiolar lesions between the inner and outer layers. These data show a characteristic distribution pattern of CLE in the transverse plane. They also suggest that the disparity in distribution of LAA between the inner and outer layers is not influenced by the grade of bronchiolar pathological lesions.