[en] The authors used high resolution volumetric CT for two-dimensional (2D) and three-dimensional (3D) measurements of skull base structures of 52 normal individuals (26 males and 26 females). Computed tomography was performed with a HITACHI W-3000 volumetric CT scanner, slice width was 2 mm, sliding speed 2 mm/sec and scan time 30 sec. We scanned the subjects in an axial plane, parallel to the orbitomeatal (OM) line from foramen magnum to rostral 60 mm, and reconstructed 59 slices of 2D-CT images every 1 mm pitch. The 3D-CT displays were derived from the 2D-CT imaging data. We measured approximately 80 points for both, 2D-CT and 3D-CT. For example, the distance of the internal acoustic meatus to the outer surface of the skull was 43.7±3.0 mm; sigmoid sinus to posterior semicircular canal, 9.1±2.4 mm; anterior clinoid process to foramen ovale, 24.5±3.1 mm; the bilateral anterior clinoid process was 27.0±3.5 mm, etc. These 2D-CT and 3D-CT measurements are useful adjuncts for surgery on the base of the skull. (author)