Three patients who were admitted for intracranial hemorrhage are reported. Cerebral angiography demonstrated an aneurysm arising from the middle cerebral artery bifurcation. No other malformation was visible either on the computed tomographic scan or on angiography. The diagnosis was ruptured middle cerebral artery aneurysm with intracerebral hematoma. At surgery, there was no blood in the sylvian fissure and the aneurysm was not ruptured. Evacuation of the hematoma and thorough exploration of the cavity led to the discovery and resection of a small vascular anomaly typical of an arteriovenous malformation responsible for the hemorrhage. Occult vascular malformations and the association of aneurysm with arteriovenous malformations are discussed. In these 3 patients, the coexistence of these two malformations could be related to a common congenital abnormality.