Protein-losing enteropathy occurred in a 7-year-old girl with tricuspid atresia, concordant ventriculo-arterial connexions and a relatively large hypoplastic right ventricle, one year after an atrio-ventricular type of Fontan operation by means of a valveless woven Dacron conduit. Severe conduit regurgitation and a marked enlargement of the hypoplastic right ventricle were demonstrated at recatheterization. Insertion of a bioprosthetic valve at the base of the right atrial appendage led to a dramatic clinical recovery of the patient. The use of a valved conduit is recommended when an atrioventricular type of Fontan repair is planned in patients with tricuspid atresia, concordant ventriculo-arterial connexions and relatively large hypoplastic right ventricle.