Xanthogranulomatous pyelonephritis is a rare and severe form of chronic pyelonephritis. Spontaneous pyeloduodenal fistula is an extremely rare complication of xanthogranulomatous pyelonephritis. We present a rare case of xanthogranulomatous pyelonephritis complicated by a complex pyeloduodenal and ureteromuscular fistulae with a cutaneous opening. A 57-year-old male patient presented with chronic right flank pain and cutaneous discharge at the right lower quadrant. Xanthogranulomatous pyelonephritis was suspected on preoperative computed tomographic urography owing to the presence of fat deposits and complex pyeloduodenal and ureteromuscular fistulae. Open nephrectomy and fistula closure were performed and the patient recovered uneventfully. Xanthogranulomatous pyelonephritis was confirmed pathologically.