We report a 19-year old woman with a choroidal-type vein of Galen aneurysmal malformation who presented with hydrocephalus. This venous malformation was fed by multiple fistulas and drained into the superior sagittal sinus through a persistent falcine sinus (precursor of the straight sinus). The hydrocephalus was treated by ventriculoperitioneal shunting, and the patient remained well for 9 years. At this time, magnetic resonance imaging (MRI) and magnetic resonance angiography demonstrated a vein of Galen aneurysmal malformation in the right thalamus, with a Chiari I appearance. This case may provide valuable data regarding the natural history of such venous malformations.