A rare case is reported of a fistula between the left internal iliac artery and the left ureter in a patient whose left kidney was the only functioning kidney. Internal iliac artery embolization was initially successful in stopping the bleeding, but the fistula recurred when the ureteral stent was removed. Even after embolization, the tissue surrounding a fistula remains very fragile, so the fistula may easily recur as a result of slight injury or inflammation.