This work was aimed at showing the main anatomical variations in the ostiomeatal complex which are usually depicted by CT. A hundred and thirty CT exams including 59 normal cases (45.4%) and 71 cases of chronic sinus disease (54.6%) were reviewed. The following anatomical variations were considered: concha bullosa, middle turbinate, septum, uncinate process and bulla changes, Haller cells and agger nasi cells. Anatomical variations were demonstrated in 69 patients--31 normal subjects and 38 patients with chronic sinusitis. The incidence of every anatomical variation was investigated and the results were compared with literature data. Excluding agger nasi cells, which were seen in nearly all patients, the most common variations were concha bullosa and septal spur and deviations, while the least common variations were those in the middle turbinate and uncinate process.