Infection is a cause of rapidly enlarging aortic aneurysms. Pseudomonas aeruginosa is an uncommon pathogen affecting blood vessels and has mainly been seen following invasive procedures in immunosuppressed patients. Pseudomonas aortitis has a high mortality. We describe a case of a rapidly enlarging juxta-renal aortic aneurysm in an immunocompetent patient who was treated with open surgery. In this patient, intra-operative specimens revealed infection with Pseudomonas aeruginosa. The patient received a long course of antibiotics and remains well at 8 months postsurgery.