Knowledge of the unique anatomy of the nose, paranasal sinuses and skull base, particular concerning dangerously low positioned or deep lying cribriform plates is most important, as functional endoscopic sinus surgery has become an increasingly popular procedure for the management of pediatric sinus disease.In addition to Keros who studied the ethmoidal roof and cribriform plate in 450 adult specimen and divided them into 3 groups, retrospective analysis in 272 patients between 0 and 14 years was performed by means of coronal CT scans of the paranasal sinuses with a slice thickness of 2 mm. Measurements were carried out in the frontal, middle and dorsal section of the ethmoid.The depth and width of the fossa olfactoria were significantly less in patients aged 0 - 12 months than in other age groups (p < 0.001). Among the other age groups, beginning at 2 years no differences were found: 14.2 % presented with type I according to Keros, 70.6 % with Keros II and 15.2 % with Keros III. The prevalence of asymmetric position of the ethmoidal roof was 15 % (41 patients). The height of the ethmoidal sinuses consistently increased over the years from 5 - 7 mm to 15 - 20 mm.The current data may serve as a reference for evaluation of normal and abnormal development of the roof of the ethmoid and may be of great value in diagnostic and therapeutic management of pediatric sinus disease. Our data obviously show that the classification into the 3 types of positions of the ethmoid roof and cribriform plate according to Keros is possible in children from the second year of life.