The primary goal of hemophilia treatment and management is the prevention of painful, disabling, and costly joint arthropathy that results from its characteristic bleeding into joints and muscles. Prophylactic treatment with clotting-factor concentrates has been shown to prevent hemophilic arthropathy and is, therefore, the standard of care for hemophilia A and B. Data has demonstrated the clinical efficacy and overall benefits of prophylaxis in young children, adolescents, and adults. Early initiation with prima-ry prophylaxis is ideal, but secondary prophylaxis in adolescents and adults has also demonstrated significant success. Because the standard of care includes prophylaxis with factor-concentrate replacement in order to prevent joint damage in patients with hemophilia, prophylaxis is now more common and needs to be addressed in all clinical settings, including managed care. However, further research is needed to help clinicians develop individualized factor-replacement protocols and under-stand the impact of long-term use into adulthood. World Federation of Hemophilia guidelines do not have definitive recommendations on continuation of prophylaxis into adulthood. The optimal regimen for initiating prophylaxis, duration of treatment, and dosing regimens continue to be studied.