PURPOSE: To re-evaluate the appearance of the anterior diaphragm by the use of MDCT. MATERIALS AND METHODS: We performed a retrospective review of 81 consecutive patients that underwent chest CT by using 64 channel MDCT. We classified the anterior diaphragm as three types (types 1-3) based on 5 mm axial scans: a line behind the xiphoid, a discontinuity and opening anteriorly, and the presence of broad and poorly defined bands. We also classified the anterior diaphragm as three types (types A-C) using 2 mm sagittal reformation images, based on the shape of the anterior diaphragmatic fibers traveling from the base of the pericardium to the xiphoid: a downward slope, an upward slope, and a flat shape, and compared the two groups using a correlation determined by statistical analysis. RESULTS: We could classify the appearance of the anterior diaphragm for all cases on the axial scans and sagittal reformation images. The number of types 1, 2, 3 on the axial scans was 30.9%, 38.3%, and 30.9% and the number of types A, B, C on the sagittal reformation images was 33.3%, 22.2%, and 44.4%, respectively. Type A was seen for 92% of type 1 cases, type C was seen for 88% of type 3 cases, and type B was seen for 54.8% of type 2 cases. The types seen between the axial and sagittal reformation images showed a significant agreement (r=0.868, p < 0.01). CONCLUSION: The shape of the anterior diaphragm correlated with the relationship between the base of the pericardium and the xiphoid.