Aorto-pulmonary window is a rare congenital cardiac anomaly characterized by a communication between the aorta and the pulmonary artery above the semilunar valves. Prenatal diagnosis is rare. We report four fetuses with aorto-pulmonary window and review the relevant literature. Approximately half of the reported cases had additional cardiac defects; none had chromosomal abnormalities. In cases with normal cardiac connections, the diagnosis can be made prenatally on the standard three–vessel view as seen in two of our cases. In one fetus with complete transposition, the diagnosis was made retrospectively on sagittal views. In the remaining case the window was seen post-natally but could not be identified retrospectively due to the abnormal supero-inferior relationship of the ventricles and vessels
