The aim of this study was to determine the prevalence and morphological characteristics of the frontal sinus in an adult population. This study was conducted retrospectively on paranasal CT scans in the axial and coronal planes of 300 cases (123 male and 177 female). The mean age was 40.74 +/- 13.34 (range 20-83). Measurements of the width, height and anteroposterior length for each sinus and total width were obtained from CT scans. Measurements were compared statistically with relation to side and sex. The cases were divided into subgroups according to age for each sex and each measurement parameter was also compared among the subgroups. All measurements tended to be larger on the left side and were significantly larger in males than females. There was a significant difference in the anteroposterior lengths of right and left sides in both males and females and height for males and width for females. In both sexes, the highest values of measurements were usually observed at the 31-40 age group and there was a tendency to decrease with aging. The larger diameters of the left frontal sinus imply that it may be more possibly violated during surgical interventions. Morphometric features differed significantly in the two sexes at different ages and comparison with previous studies presented great regional variability. The size of the frontal sinus was seen to be related to age and sex. The knowledge provided in the present study is useful for some surgical procedures and widens the anthropometric knowledge of humanity.