PURPOSE: To assess the usefulness of multi-slice spiral CT in the evaluation of aortic arch and airway in children with obstructive aortic arch. METHOD AND MATERIALS: In 45 patients with obstructive aortic arch, 55 preoperative or postoperative CT examinations (median age, 3 months; age range, 2 days[dash]years) using multi-slice CT were performed between June 2000 and February 2003. They included 14 patients with interrupted aortic arch and 31 patients with coarctation of the aorta. The location and degree of aortic arch obstruction were evaluated. Except for four preoperative patients with interrupted aortic arch, the degree of aortic arch stenosis was calculated from the diameters of the narrowest aortic arch and the descending aorta at the level of the diaphragm. Based on echocardiographic, catheter angiography, or surgery, 51 CT studies with aortic arch stenosis were divided into three clinical groups having no (n = 25), borderline (n = 5), or significant (n = 21) stenosis. The degree of aortic arch stenosis at CT was compared among to three groups. In the aortic arch abnormalities, the diagnostic performance of CT was compared with that of echocardiography. In the airway abnormality, the location and probable cause were evaluated. The effect of CT findings on surgical management was assessed. RESULTS: The degree of aortic arch stenosis at CT was 18.4[plusminus]15.7% in patients with no significant stenosis, 44.7[plusminus]7% in patients with borderline stenosis, and 59.8[plusminus]15.5% in patients with significant stenosis. The degree of stenosis showed statistically significant differences but overlapped among three groups. In the evaluation of the aortic arch, CT and echocardiography were comparable in 45 studies, CT was better in nine, and echocardiography was better in only one. The left main bronchus was the most frequent location (n = 26) of narrowing among 32 airway abnormalities. 21 cases of narrowing at the left main bronchus were owing to the tightened aortic arch. Surgical management was modified according to CT findings in six patients. CONCLUSIONS: Multi-slice spiral CT appears to be useful in the evaluation of the aortic arch and airway in children with obstructive aortic arch.