A 2-year-old boy presented for evaluation of a systolic murmur. Echocardiogram demonstrated dilated left main and right coronary arteries. Selective injection of the left coronary artery confirmed dilation of the left main and anterior descending coronary arteries. The left anterior descending coronary artery subsequently filled the mid portion of the right coronary artery retrograde, which emptied into a blind fistula. The orifice of the right coronary artery was atretic, with no filling from the aortic root or the fistula.