Aorta to right ventricular fistula is a rare complication of ascending aortic dissection that has previously been diagnosed ante mortem only by cardiac catheterization. This report describes a patient who had aorta to right ventricular fistula that caused a left-to-right shunt and marked hemodynamic instability. An anatomic diagnosis was made rapidly in this patient by use of echocardiographic techniques. Two-dimensional and Doppler echocardiography have an important role in defining the cause of cardiovascular collapse after aortic dissection.