Aim: A lot of variations may be noticed in shape and size in mastoid air cells. CT in diagnosis, although many studies were done, by using in these studies age groups were not usually established and the volumes of mastoid air cells were not compared in detail. Therefore in this study, it was planned the classification of mastoid pneumatization, the relationship between right and left sides and the comparison of development progresses according to the age and sex with the results of the CT scans.

Material and Method: Of all patients applied to radiology department, 91 cases without any mastoid air cells pathology (like inflammation, operation or trauma) were selected for evaluation. Axial CT scans obtained from temporal bones of all cases. In all scans, the volumes of each area mastoid air cell were calculated and analysed statistically.

Results and Conclusion: At the results, it was noticed that the volumes of mastoid air cells increased with the age and women had lower mean volume. When we correlated right-left and ipsilateral structures mastoid air cells, it was determined that there was a positive correlation between them. The mean volumes were near to the results on the literature. The percentage of pneumatic mastoid was 97.80 %, apneumatic mastoid was 2.19 %.