A previously healthy 77-year-old woman with a 4-week history of back pain and fever was admitted to our hospital for chronic type A aortic dissection. The aortic arch was enlarged to 7.5 cm in diameter, and the large dissecting aortic aneurysm involved all three branches of the aortic arch and compressed the trachea. Laboratory tests showed an increased C-reactive protein level (10.5 mg/dl). Blood cultures performed upon admission were negative. Progression of the symptoms suggested the possibility of impending aneurysm rupture. The patient underwent urgent total arch replacement, and cultures of samples obtained from the aortic wall during surgery were positive for Listeria monocytogenes. Two months after surgery, advanced rectal cancer was diagnosed. It is believed that the rectal cancer predisposed the patient to development of an arterial infection associated with L. monocytogenes.