Between 1982 and 1989, nine patients with complete atrioventricular (AV) canal and tetralogy of Fallot underwent successful repair of both anomalies. Seven patients had Down's syndrome. One or more previous palliative shunts had been used in six patients. Associated cardiovascular lesions included persistent left superior vena cava (two patients), patent ductus arteriosus with marked stenosis of the left pulmonary artery (one patient). The diagnosis was confirmed by cardiac catheterization and cineangiography. Closure of the ventricular septal defect was performed through a combined right atrial and ventricular approach in each patient. The right ventricular outflow obstruction was relieved with the use of a transannular patch (4), right ventricular infundibular patch (4) or a valved external conduit (1). There were no hospital deaths. One patient died as a result of meningitis 2 years after repair. Progressive left AV valve incompetence developed in one patient requiring valve replacement. A single atrial approach may not provide the best exposure of the subaortic end of the defect. In this regard, we recommend an additional right ventriculotomy in order to ensure safe closure of the septal defect. Although an adequately shaped isolated patch could be sufficient to close the anterior VSD, we favour a separate patch to minimize the possibility of producing subaortic obstruction. A further method to avoid this subaortic stenosis consists of dividing the common anterior leaflet to the right towards the lateral extent of the infundibular septum.