We describe six patients with situs solitus of viscera and atria, dextrocardia, atrioventricular discordance, ventricular septal defect, double outlet from the morphological right ventricle, pulmonic stenosis and levomalposition of the aorta. Four patients were male and two female; their age ranged from 3.5 to 31 years (mean 13.8 years). All had various degrees of disability, and presented with cyanosis, clubbing and high hematocrit levels. One patient had an atrio-ventricular block that varied from first to third degree; another patient showed intermittent junctional rhythm. At angiography the ventricular septum appeared to be almost perpendicular to the frontal plane in most cases, so that the anteroposterior projection resulted in a true axial view. One overriding left atrioventricular valve and one straddling right atrio-ventricular valve were demonstrated; no significant incompetence of either valve was observed. The ventricular septal defect was always single and related to the subpulmonary outflow. Pulmonic stenosis was valvular in every patient; an additional infundibular obstruction was present in one case. In two cases an additional stenosis was discovered at the supravalvular level. The left pulmonary branch was stenotic in one case; it was hypoplastic, with controlateral dilatation, in two cases; both pulmonary arteries were dilated in one case. The aorta was always to the left of the pulmonary artery, either anterior or side by side. Three patients were operated on in different Institutions: one had a pulmonic valvotomy at the age of six years; one, aged twenty, had a right Blalock-Taussig shunt; the third, with overriding left atrioventricular valve, underwent a modified Fontan operation at the age of thirty years with success.(ABSTRACT TRUNCATED AT 250 WORDS)