A 25 year old asymptomatic man with a past history of pulmonary tuberculosis presented with a continuous murmur. Selective arteriography revealed a left internal mammary arteriovenous malformation in communication with vessels in the left upper pulmonary lobe. No significant hemodynamic abnormalities were detected. This is the 26th reported case of internal mammary arteriovenous fistula and the 6th with a pulmonary communication. Review of the data in previous cases suggests that surgical indications are limited to symptomatic relief, heart failure during infancy or the possible risk of endarteritis, proximal arterial degeneration or rupture.