One year after total correction of tetralogy of Fallot, reoperation was performed in a 2-year-old infant because of an aneurysm of the right ventricular outflow tract. After removal of the aneurysm, massive right ventricular failure occurred. Maximal medical inotropic support could not reestablish sufficient right ventricular function. Therefore, it was decided to implant the new HIA-Medos system as a right ventricular assist. In the postoperative period, echocardiographic controls showed increasing contractility of the right ventricle. The assist system was removed after 3 days and the infant was discharged in good condition on the 22nd postoperative day.