A fifty eight year old man with Marfan's syndrome and an aortic composite graft with a Bjork-Shiley mechanical prosthesis presented with a large aortic root abscess caused by Staphylococcus aureus endocarditis. Despite extensive surgical debridement and implantation of an aortic homograft as a composite graft, early postoperative transoesophageal echocardiography continued to demonstrate a large aortic root abscess and the patient died in a septic shock.