We report on five newborns with an arterio-venous malformation of the vein of Galen. All newborns were cyanotic and in congestive heart failure without any evidence of congenital heart disease. Congestive heart failure in these cases was mainly due to an almost two-fold increase in cardiac output of approximately 8 l/min/m2 (normal: 4.5 l/min/m2). According to previous reports, mortality is very high in patients with this malformation when becoming symptomatic during infancy, and therapy by surgery or embolization is only successful in 10-30%. While three of our patients died shortly after diagnosis because of untreatable heart failure, the other two were operated on either by subtotal ligation of the draining vein or by ligation of 4 arterial feeders. In the first case secondary thrombosis of the aneurysm occurred and cardiac failure subsided. In the second case a large shunt remained and a balloon-embolization was performed successfully. However, in both patients severe neurologic defects occurred, the severity of which remains to be assessed later since the post-operative observation period is only 2 and 5 months, respectively.