Systemo-pulmonary fistulae are rare. The case of a 27 year-old man, hospitalized for exploration of a continuous thoracic murmur, is reported. A right pleurectomy had been performed 2 years previously because of a recurrent spontaneous pneumothorax, and no murmur was present at that time. Angiography showed a systemo-pulmonary fistula with the right internal mammary artery and branches of the right axillary artery as afferent vessels, and the right pulmonary arteries and veins as efferent vessels. Blood gases measurements demonstrated a left-right shunt. The acquired nature of the fistula was suspected because of the history of right pleurectomy and the acquired nature of the murmur. There was no indication for surgery because of the complexity of the fistula and the absence of symptoms.