Radiologic evaluation of frontal sinus fractures is instrumental in determining the need for surgery. Computed tomography (CT) is an excellent modality for evaluation of frontal sinus trauma, particularly for anterior and posterior wall fractures. However, fractures of the nasofrontal duct are more difficult to delineate, and judgments about operating for this problem are often made on less than concrete evidence of duct trauma. To evaluate the usefulness of CT in identifying nasofrontal duct trauma, a two-part study was done. First, CT was performed on cadavers to study the anatomic relationship of the nasofrontal duct to midface anatomy. Then, a retrospective study was performed in 19 patients with suspected frontal sinus fractures who underwent frontal sinus surgery. Findings at surgery were compared with preoperative evaluation with CT. Correlations were identified and criteria developed that can be used to identify patients needing surgical intervention in frontal sinus trauma. These criteria include findings of either a fracture involving the base of the frontal sinus or a fracture of the anterior ethmoid complex, or both.