Background: True internal mammary artery aneurysms are rare but rupture has been described.
Case Report: A 39-year-old male patient with Marfan syndrome was diagnosed with large asymptomatic bilateral internal mammary artery aneurysms (IMAAs) on contrast-enhanced CT scan, without other arterial lesions. Both aneurysms were coil embolized, a stent graft was deployed in the left subclavian artery to cover a wide neck that precluded complete and safe embolization of the left IMAA.