The purpose of this study is to determine important variations and areas of risk for major complications in paranasal computed tomography (CT). We also made specific measurements for individual differences. This study consisted of 64 children (128 sides). Eleven participants had coronal and axial, and the remaining 53 only coronal CT. The distance of the anterior ethmoidal artery (AEA) and the lamina cribrosa to the inferior turbinate and the orbital roof, and the depth or the lamina cribrosa were measured. The percentages of some of the variations were as follows: upper attachment of uncinate process 25%, freely coursing AEA 43%, aerated anterior clinoids 8%. optic canal bulging 6% and extreme medially coursing carotid canal 3%. The frequencies of some of these variations and the existence of Onodi cells were significantly smaller than compared with adults. Specific measurements varied individually. In conclusion, children deserve more attention while evaluating CT, due to their tiny bony structures. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.