We report the temporary use of a Berlin Heart ventricular assist device (Berlin Heart AG, Berlin, Germany) for cardiac support of an 18-month-old girl with rapidly progressive ventricular failure after completion of a fenestrated Fontan. After 6 months of cardiac assistance with a single pneumatic pump, catheterization data showed improvement of the ventricular function and the ventricular assist device was successfully removed. A follow-up echocardiogram 6 months after hospital discharge demonstrated marked improvement of ventricular function.