A case of spontaneous perirenal hemorrhage in an anticoagulated patient is reported. Spontaneous perirenal hemorrhage is uncommon and is seldom suspected clinically. Elderly subjects are exposed to a higher risk of bleeding complications during warfarin treatment. A 60-year-old female experienced acute right flank pain after receiving warfarin for 4 days. Detailed imaging modalities demonstrated the presence of perirenal hematoma and angiomyolipoma. The patient was treated conservatively and followed up with ultrasonographic and computed tomographic scans until the hematoma was almost completely reabsorbed. No surgical intervention was needed, and the patient recovered well.