Arteriovenous fistula is a relatively rare cause of severe congestive heart failure in the newborn. An intracranial arteriovenous malformation associated with an aneurysm of the great vein of Galen is the most frequent of such malformations and, although well known, it remains a difficult diagnosis in the neonate because the clinical picture first presents with findings suggesting cardiac disease. The newborn with a vein of Galen aneurysm has volume and pressure overload on his myocardium; cyanosis is often present due to persistent fetal circulation; peripheral pulses are generally decreased in amplitude except in those arteries near the fistula where they are bounding, as an expression of a hyperdynamic status. A continuous murmur may be heard over the scalp, but this highly suggestive sign is often not present. The majority of newborns with intracranial arteriovenous fistula die very soon. Unfortunately, most of these infants are at first considered to have congenital heart disease and are, therefore, subjected to cardiac catheterization and angiography, with their well-known risks, before a correct diagnosis is made. Cross-sectional echocardiography, by demonstrating normal intracardiac anatomy, eliminates the need for an invasive investigation in a very sick neonate. Ultrasonography of the head will then provide a rapid and accurate demonstration of the aneurysm of vein of Galen. Cerebral angiography will complete the diagnosis in those cases in which a neurosurgical intervention is contemplated.