The aim of the present study was to assess the diagnostic accuracy of CT in determining the underlying causes of brain hematomas with a state-of-the art CT. For this purpose, CT and angiographic data of 149 subjects with spontaneous intracerebral hematomas (ICH) were statistically compared in a blind, retrospective study, taking angiography, supported when possible by surgical findings, as providing the correct diagnoses. 5 groups were distinguished on the basis of CT data: 103 patients with isolated deep ICH had normal angiograms; 9 patients with isolated superficial ICH and 8 with deep ICH and intraventricular hemorrhage (IVH) had arteriovenous malformations (AVMs). 4 with this combination showed no angiographic abnormalities, one had an aneurysm. 14 subjects with ICH and subarachnoid hemorrhage (SAH) had a middle cerebral or carotid artery aneurysm; and 10 with ICH, SAH and IVH had also an aneurysm, in 7 on the anterior communicating artery. Sensitivity, specificity, positive and negative predictive values were respectively: for AVMs 100, 96, 77 and 100%; and for aneurysms 96, 100, 100 and 99%. Kendall coefficient was 0.95, indicating close correlation between the two modalities. This study confirms that CT can accurately predict the likelihood, nature and location of vascular ICHs. It indicates whether angiography is necessary or not, and if so, what vascular tree ought to be explored.