The most common clinical manifestation of hemophilia is intraarticular bleeding (hemarthrosis). Although any joint can be involved, the articulations most frequently affected are the knees, elbows, and ankles. Hemorrhages may occur spontaneously, or as a result of trauma. Because hemophilia is a genetically determined coagulation disorder, the bleeding incidences may start early in a child's life. After several hemarthroses, hemophilic synovitis will develop and, because of the profusion and fragility of vessels within the tissue, will lead to a vicious cycle of bleeding-synovitis-bleeding. If the synovitis is not controlled, cartilage damage will occur. hemophilic arthropathy then will become apparent clinically and radiographically, causing functional impairment of the affected joint. Prophylaxis and early diagnosis of acute hemarthrosis are essential to prevent the development of hemophilic synovitis. Hemarthroses must be treated aggressively if hemophilic synovitis is to be prevented. Continuous prophylaxis from age 2 to 18 years has been claimed to reduce the incidence of chronic hemophilic synovitis and joint damage, which remain the main causes of disability in the life of the patient who has hemophilia.