Abstract: Objective: To assess the clinical value of 256i CT angiography in the arteriosclerotic occlusive disease(ASO) of lower extremity.Methods: A total of 119 patients with symptomatic arteriosclerotic occlusive disease of lower extremity underwent 256i CT angiography.The scan ranged from the celiac to thenar artery.Original axial images were transferred to EBW workstation and 3D reconstruction images were performed.75 patients underwent digital subtraction angiography(DSA) between 0 and 14 days after CT angiography.The manifestations of 256i CT angiography were compared with those of DSA.Results: Of 1575 segments of arteries,1505 were displayed on both DSA and CTA.DSA images as the gold standard,the sensitivity,specificity and accuracy of 256i CTA were 100.0%,98.8%,99.7% in displaying the segments occluded and 99.3%,97.8%,98.2% in detecting the segments that had more than moderate stenosis.Therefore,there was excellent agreement between 256i CT angiographic and DSA findings in the assessment of ASO(k=0.945).Of 975 segments,905 were found atherosclerotic plaques,12 were simple mural thrombus.Conclusion: The diagnostic performance of 256i CT angiography is excellent in patients with clinical symptoms of the arteriosclerotic occlusive disease of lower extremity.The results can be used to effectively guide therapeutic decision making in these patients.