An autopsied case of arteriovenous aneurysm of the vein of Galen in a 31/2-month-old female is reported. Arteriovenous aneurysm of the vein of Galen is a rare vascular malformation of the central nervous system consisting of a saccular dilatation of the vein which receives blood shunted through enlarged arteries. These peculiar structural and hemodynamic characteristics differentiate this particular malformation from the other AVMs of the central nervous system. In infants the arteriovenous aneurysm of the vein of Galen is characterized clinically by hydrocephalus and cardiomegaly. In the present paper the clinical features and diagnostic indications are discussed and, in particular, the role of computerized cranial tomography (CT) is emphasized as a rapid and noninvasive procedure for detection of intracranial disorders.