PURPOSE: To assess the diagnostic capability of three-dimensional CT angiography(3D-CTA) in the diagnosis of intracranial aneurysms, compared with conventional angiography. MATERIALS AND METHODS: Twenty-two patients with intracranial aneurysms were studied using 3D-CTA and conventional angiography. Three-dimensional images were obtained with a helical CT scanner using SSD(shaded surface display) technique. 3D-CTA findings were retrospectively compared with conventional angiography with respect to lesion detection and delineation of the aneurysms. RESULTS: Of the 25 aneurysms demonstrated by conventional angiography, 23(92.0%) were detected by 3D-CTA. Aneurysmal necks were clearly visualized in 17 of 25 aneurysms(68.0%) with conventional angiography, and 19 of 23(82.6%) with 3D-CTA. And 3D-CTA is also superior to conventional angiography in aneurysmal delineation. CONCLUSION: 3D-CTA is thought to be a potential imaging modality in the evaluation of intracranial aneurysm, especially in aneurysmal delineation.