A 73-year-old man was admitted for investigation of back pain, blood-stained sputum, and a high fever. Computed tomography (CT) showed a pseudoaneurysm in the descending aorta and intravenous antibiotic therapy was begun immediately after blood had been taken for culture. However, his temperature continued to spike daily, up to 38 degrees C, and his CRP was also elevated. The blood cultures were negative. The aneurysm ruptured and we replaced the descending aorta with a rifampicin (RFP)-soaked vascular prosthesis, and wrapped it with greater omentum. Postoperative antibiotic therapy with vancomycin hydrochloride, RFP, and amikacin sulfate was continued for 8 weeks. The patient recovered uneventfully. Thus, an infected aneurysm was effectively treated with a RFP-soaked vascular prosthesis and omentopexy.