Three cases of endovascular infection of atherosclerotic aneurysm of the abdominal aorta due to Salmonella spp. are described. 'Breakthrough' or relapsing bacteraemia were major clues for diagnosis in each case. They were treated with a prolonged course of bactericidal antibiotics before surgery. Resection with an interposed graft was performed in all cases and antibiotic treatment continued. Two of our patients have survived for more than two years and the other for 18 months without evidence of relapse. Thus, it would appear possible at times to treat successfully mycotic aneurysm of the abdominal aorta with antimicrobial agents plus resection of the aneurysm followed by in situ bypass grafting. Extra-anatomical grafts should be kept for infections due to antimicrobial-resistant organisms or when periaortic infection is widespread.