A 2-month-old infant died of xanthogranulomatous pyelonephritis. Preoperatively pyonephrosis was suspected, because the child presented with a number of inflammatory, septic symptoms. Nephrectomy was performed and histopathology showed the kidney to be affected by xanthogranulomatous pyelonephritis. Postoperatively the child developed persistent attacks of fever and bronchopneumonia that led to his death with signs of pulmonary insufficiency.