Pulmonary atresia with intact ventricular septum has been described extensively, and it is recognized that associated abnormalities of the coronary arteries may cause ischemia. We describe a fetus, diagnosed antenatally as having pulmonary atresia with intact ventricular septum and severe hypoplasia of the right ventricle, who developed severe left ventricular dysfunction. We hypothesize that this is due to reduced coronary blood flow because of falling right ventricular volume in the presence of complete right ventricular coronary arterial dependence.