This report describes a premature newborn with pulmonary atresia and an intact ventricular septum who presented with a significant fistula between the right ventricle and the left anterior descending coronary artery (LAD). The right ventricle was not decompressed to prevent myocardial damage. After 2 months, the fistula had closed spontaneously. The pulmonary valve was opened, and biventricular circulation was achieved.