The development of an aorto-right ventricular fistula is a rare complication of cardiac surgery. The most common treatment is surgical closure of the fistula, but percutaneous closure of the fistula has become an attractive alternative option. We present a case of successful utilization of live/real time three/four-dimensional transoesophageal echocardiography (3/4DTEE) to select the correct device size for percutaneous closure of an adult patient presenting with an aorto-right ventricular (AO-RV) fistula following aortic valve replacement. To the best of our knowledge, this is the first case in which 3/4DTEE was used to select the device size and guide percutaneous closure of an iatrogenic AO-RV fistula.