Objective To evaluate the role of digital subtraction angiography (DSA) in the detection of intracranial aneurysms among patients with spontaneous subarachnoid hemorrhage (SAH) compared with computed tomographic angiography (CTA) in a single center, Sri Lanka. Methods A total of 123 patients clinically and CT proven SAH were evaluated with CT angiography and DSA with a median interval of 3 days. The sensitivity, specificity and accuracy of CT angiography in detecting aneurysms were analyzed compared to DSA on a per-patient, per-size, per-site and per morphological basis. All data were analyzed using SPSS analytical package (version 18). Ethical approval for the study was from the institutional ethical review board. Results Among 123 patients with clinically and CT proven SAH, 51 (41.5%) patients showed aneurysms on CT angiography. 72 were negative for aneurysms in CTA. In 13 out of 72 (18%) CTA negative patients subsequent DSA demonstrated aneurysms. Number of CTA negative but DSA positive aneurysm were 15 as two of the patients had two aneurysms each. Four CTA detected aneurysms could not be appreciated in the subsequent DSAs. Aneurysms (47)detected by both CT angiography and DSA were more than 6mm in size (56.7%) , sacculartype (96.5%) and were located in the anterior circulation system (92.4%). Most CTA negative aneurysms detected by DSA were less than 6mm in size (80%), saccular type (60%) and were located in anterior (53.8%) and posterior (46.7%) circulation system. The sensitivity, specificity, positive predictive value and negative predictive value of CT angiography compared to DSA per patient basis were 78.3%, 93.7%, 92.2% and 81.9% respectively. CT angiography has a low sensitivity to detect aneurysms less than 6mm size (65.7%%), in posterior circulation (36.4%) and other morphological types (0%) compared to aneurysms more than 6mm size (90.9%), in anterior circulation (85.9%) and saccular type (85.5%). Conclusion Digital subtraction angiography (DSA) has a significant role in detecting intracranial aneurysms which are less than 6mm in size, are located in posterior circulation system and of non-saccular morphological type.