A 46 year-old woman with perinephric type of xanthogranulomatous pyelonephritis is described. She had a fever and pain with a palpable mass in her right flank. The blood analysis revealed anemia, leucocytosis, gamma-globulinemia, but no hyperlipidemia. The urine analysis showed nothing abnormal, but enterobacter was present in the urine. An intravenous pyelogram demonstrated a right non-functioning kidney. The diagnosis of a perinephric abscess was made from the x-ray and ultrasonogram, and a right nephrectomy was performed. The resected kidney had a tumor-like lump covered with Gerota's fascia at the postero-lateral side of the kidney. The cut surface of the kidney revealed an area of hemorrhage, blood clotting, abscess and a brownish yellow area in the perinephric fat tissue. The calyx and pelvis were normal. Histologically, the brownish yellow area was a granuloma with foam cell infiltration. The foam cells contained lipids. The renal parenchyma showed a non-specific chronic pyelonephritis.