Objective To study the value of 64-slice spiral CT digital subtraction technique in the diagnosis of intracranial aneurysms.Methods 36 patients with subarachnoid hemorrhage underwent 64-slice spiral CT examination,including unenhanced CT scan and enhanced CT scan.The image data were used to reconstruct the conventional CTA and digital subtraction CTA(DSCTA).Then the differences of image quality and diagnostic efficiency between the CTA and DSCTA were compared based on the standard of DSA . Results There were 40 intracranial aneurysms in 36 patients . 40 aneurysms were detected completely by DSCTA,the sensitivity and specificity of the DSCTA were both 100% . 37 aneurysms were detected by CTA , and the sensitivity and specificity were 92.5% and 100%,respectively.There was significant difference in image quality between CTA and DSCTA(P＜0.01).Conclusion DSCTA with 64-slice spiral CT might be the first diagnostic tool in screening intracranial aneurysm.