We describe the case of a patient with a culture-proven infection of the ascending aorta caused by Legionella pneumophila 16 months after cardiac transplantation. Serology follow-up and surveillance culture of the hospital water supply suggested a nosocomial acquisition of the infection during the post-transplantation period. The diagnosis was made after 5 months of recurrent unexplained febrile episodes. A Teflon ring implanted around the aortic suture line during the intervention may have contributed to the unusual localization of the infection. The patient was successfully treated with antibiotics and aortic reconstruction.