An intracranial dural arteriovenous fistula(dAVF)was incidentally detected in a 39-year-old man during a medical checkup. Except for a mild episode of pneumonia at the age of 22 years, his medical history was unremarkable. He had no family history of hereditary hemorrhagic telangiectasia(HHT). The dAVF was treated radically via ligation of the fistula, without any complications. Postoperative angiography demonstrated that the dAVF had completely healed, but showed an aberrant, dilatated, and tortuous internal mammary artery. A contrast-enhanced computed tomography scan revealed multiple arterio-arterial fistulas between various systemic arteries and the pulmonary artery(an intercostal artery to the pulmonary artery fistula, an internal mammary artery to the pulmonary artery fistula, and an inferior phrenic artery to the pulmonary artery fistula). These thoracic lesions did not require additional treatment because they did not cause any symptoms, e.g., respiratory or cardiac failure. In most previous cases, such aberrant thoracic arterial fistulas were detected incidentally or based on the presence of minor clinical symptoms. However, in some cases, they caused severe respiratory or cardiac failure and were treated via the embolization of the responsible vessels. Therefore, the co-existence of thoracic arterial fistulas in patients with dAVF should be evaluated, even if the dAVF does not meet the criteria for HHT. Such thoracic lesions might cause a chest murmur that can be detected via a stethoscope or via a blunt costophrenic angle on chest radiography.