We report on a 22-year-old woman with a continent urinary diversion in whom acute renal failure developed on ciprofloxacin therapy for pelvic osteomyelitis. Renal failure resolved rapidly once the drug was withheld. Because ciprofloxacin is used extensively by the urological community, we believe that it is important to be aware of this potential complication of therapy. We review the literature on the association of ciprofloxacin and renal failure.