An 87-year-old man with an abdominal aortic aneurysm received intravesical bacillus Calmette-Guerin therapy for transitional cell carcinoma of the bladder. He presented 9 months later with a psoas abscess that mimicked a contained retroperitoneal abdominal aortic aneurysm rupture. The abscess cultures yielded Mycobacterium bovis. Recent transurethral resection and high voiding pressures after instillations of bacillus Calmette-Guerin may have led to distant dissemination of the drug.