A case of subcapsular hematoma, a rare complication of acute pyelonephritis (APN) is described. A 60-year-old diabetic woman was admitted with a 3 day history of fever and left flank pain due to acute pyelonephritis. On the third day in hospital, left flank pain worsened despite use of antibiotics available for the treatments of APN and hemoglobin rapidly decreased from 11.1 to 7.9 g/dL. Ultrasonography and abdominal CT showed left subcapsular hematoma. Renal angiography demonstrated an ovoid avascular zone between the capsular artery and parenchyme of the left kidney with no evidence of tumors or vascular abnormalities, such as arteriovenous malformation or fistula. Subsequent percutaneous drainage of this subcapsular hematoma was performed and showed old blood-colored drainage. Hereby, the possibility of subcapsular renal hematoma in the course of acute pyelonephritis is stressed as a rare complication.