We present a case of spontaneous retroperitoneal hemorrhage secondary to anticoagulant therapy. A 41-year-old woman who underwent aortic valve replacement due to infective endocarditis 2 months ago was admitted for evaluation of dizziness and fatigue. Physical examination revealed the abdomen to be distended. Blood work showed a hemoglobin 4.5 and INR 3.5. Abdominal CT showed a huge intra-abdominal hematoma with right internal iliac artery rupture. In abdominal aortic angiography, rupture of right internal iliac artery was confirmed and treated with embolization. Bleeding stopped after embolization, but she developed acute renal failure secondary to a huge hematoma. On POD#4, she underwent a laparotomy and the hematoma was evacuated. The patient had an uneventful recovery and was discharged from the hospital with no further bleeding episodes.