The hemorragic episode is the major problem of mechanical prosthesis, because of the necessity for anticoagulant therapy to prevent complication of thromboembolism. Double valve replacement was performed to 42 year old male due to aortic stenoinsufficiency and mitral stenosis. For anticoagulant therapy, the patient has been given wafarin under the control of prothrombin time 0.5-2 times of normal) in the our hospital. The patient was injuried the right pelvic area by waves in the beach 4 years after double valve replacement. Pelvic MRI scan showed huge hematoma in the right pelvic cavity. The patient was operated removal of intrapelvic hematoma.