Variability studies on frontal sinuses, covering the age range from childhood to adulthood have been neglected in literature up to now. On a total of 215 children and youths from 3-17 years (117 boys and 98 girls), the growth rate of the frontal sinuses had been examined. The difference between males and females proved to be quite interesting. The frontal sinuses of girls increase evenly in size during the years, whereby from 1-5 years the development runs parallel with boys and girls. From 8-12 years the growth rate of male frontal sinuses is very low, causing a retardation of growth on boys in comparison to girls. After that period, however, a substantial acceleration of the growth rate takes place, so, that at the age from 14-15 years the frontal sinuses of the males have surpassed the female ones referring to size. At the age of 18 years the forming of frontal sinuses can be considered as finished.