A direct communication between the left ventricle and right atrium is a relatively uncommon defect. Familiarity with this anomaly has become increasingly important, however, since the preoperative findings may be identical with those of an atrial septal defect. The left ventricle is directly related to the right atrium over. an area of the membranous ventricular septum which extends superior to the septal attachment of the right atrioventricular valve in the LV-RA communication. The clinical triad of a ventricular septal defect murmur, cardiac enlargement, and an arteriovenous shunt at atrial level is characteristic of the malformation. A 2-year-old boy with left ventriculo-right atrial communication has operated at the Maryknoll Hospital. Under the cardiopulmonary bypass, the atrium was opened, there was a jet-blood stream just above the atria-ventricular portion adjacent to the septal leaflet of the tricuspid valve.