Evaluating complex cardiac defects in small children preoperatively requires multiple diagnostic procedures including echocardiography, but also the invasive methods such as cardiac catheterisation, computer-tomography and magnetic resonance imaging. We tried to assess the complex anatomy of the atrioventricular valves in atrioventricular septal defect using bedside real-time three-dimensional echocardiography and comparing these results to the anatomic findings at the time of operation.