Controversy regarding the optimal preoperative evaluation for patients with carotid arterial stenosis remains controversial. We hypothesized that carotid artery area reduction measured by computed tomography angiography (CTA) would closely correlate with duplex scanning stenosis. This study was undertaken to evaluate the correlation between duplex, CTA, and conventional arteriography in patients undergoing consideration for carotid endarterectomy. Patients undergoing evaluation for carotid artery stenosis who received at least 2 of the diagnostic tests were included in this study (n = 108); 30 patients underwent all 3 imaging modalities. Linear regression analysis was performed to determine correlation coefficients between the 3 different study modalities. Correlation and P values were as follows: CTA area versus CTA diameter, r = 0.82, P < 0.001; CTA area versus duplex stenosis, r = 0.71, P < 0.001; duplex stenosis versus angio diameter, r = 0.68; P = 0.005; CTA diameter versus angio diameter, r = 0.61, P = 005. CTA was able to identify plaque characteristics more readily than duplex or arteriography. CTA was also able to differentiate critical stenosis from occlusion and to settle discrepancies obtained from duplex scanning. CTA is an acceptable alternative method to validate duplex scanning evaluation of carotid artery stenosis. It can accurately measure lumen stenosis, visualize plaque morphology, and is associated with fewer complications than conventional angiography.