Surgical palliation of univentricular hearts by a modified Fontan operation has become a useful procedure for these complicated cases. Closure of the right atrioventricular valve is an important part of the operation. Patch closure has been the technique used by most surgeons. Heart block and dehiscence of the patch have been two common complications of this technique; both involve severe hemodynamic upset and often death to the patients in the early postoperative period. We closed the right atrioventricular valve by approximating the leaflets using pledgeted mattress sutures in two patients. Advantages of this type of closure are avoidance of the conduction system and secure closure of the valve.