This is a rare congenital abnormality with only 17 other reported cases in the world literature. The most frequent sign is cyanosis with peripheral arterial desaturation. Angiography with selective injection in the main pulmonary shows early opacification of the left atrium, so confirming the diagnosis. Occasionally, a catheter can be passed through the fistula. Without surgical treatment there is a danger of systemic arterial embolism and two fatal cases were found in our review of the literature. The fistulous connection is often aneurysmal. It arises either from the right main pulmonary artery or from its branch to the inferior lobe. Associated vascular and pulmonary malformations are not rate. Surgical closure of the fistual is curative with immediate regression of the cyanosis and suppression of possible embolic complications.