We report the ante-natal diagnosis of a vein of Galen aneurysm using colour flow Doppler at 33 weeks gestation. Ultrasound demonstrated a midline, tubular, echo-free structure superior to the thalamus extending posteriorly. Venous flow was demonstrated within the structure using colour flow Doppler. The diagnosis was confirmed by post-natal sonography. We believe this to be the first ante-natal diagnosis of this condition using colour flow Doppler.