Conventional cerebral angiography has always been regarded as the gold standard for intracranial aneurysm detection. However, conventional angiography has the disadvantages of being invasive and time consuming. We present here 30 patients who underwent computed tomographic angiography (CTA) with three-dimensional reconstruction for the detection of intracranial aneurysms. All of these patients had subarachnoid hemorrhage or suspected intracranial aneurysms. CTA was performed in all patients with the use of a General Electric Hispeed Advantage helical scanner. Iohexol, 135 ml, was used as the contrast agent. Twenty-five patients also underwent conventional angiography for comparison. The five patients who underwent CTA only did not have conventional angiography because of poor clinical condition, and four of them subsequently died. Five patients had subarachnoid hemorrhage, but the results of both CTA and conventional angiography were negative for aneurysms. One patient had an incidental finding of a 3-mm left posterior communicating artery aneurysm on CTA, which was confirmed by conventional angiography. In the remaining 19 patients, 19 saccular aneurysms and 1 fusiform aneurysm were detected by CTA. Locations and sizes were confirmed by conventional angiography in all except two. The first exception was a patient who had a 2.5-mm anterior communicating artery aneurysm detected by CTA but not by conventional angiography. Surgical exploration confirmed the CTA diagnosis. The other exception was a patient in whom a 2-mm right posterior communicating artery aneurysm was detected by CTA but in whom conventional angiography showed a 2-mm left posterior communicating artery aneurysm. Unfortunately, there was no surgical confirmation in this case because the family of the patient refused surgery. Our results have demonstrated that CTA is a quick, reliable, and relatively simple diagnostic tool for intracranial aneurysms. In an emergent situation, such as a deteriorating patient with a hematoma, it is superior to either empiric exploration or infusion computed tomographic scans because it delineates the orientation and configuration of the aneurysm and its associated vascular anatomy.