The present study was performed on axial and coronal CT scans of 212 patients. Scans were analyzed by an anatomist and a radiologist for the presence of Haller's cells, agger nasi cells, Onodi's cells and pneumatized crista galli. Results demonstrated the presence of Haller's cells in 21.2%, Onodi's cells in 10.4% and pneumatized crista galli in 2.4% of patients. A pneumatized anterior clinoid process was found in 0.5% of the patients. The data obtained in our study were compared with those reported in other anatomic and radiologic studies.