Although hemophilia has been recognized for centuries as an inherited disorder primarily affecting males, advances in treatments have been very recent. Initial availability of plasma-derived therapies offered significant improvements in morbidity and mortality, but the transmission of viruses quickly negated the benefit of early factor replacement products. After developing successful viral inactivation methods and subsequently developing recombinant technology, the manufacturing of factor concentrates became much safer. Access to safer factor products allowed for a shift from the treatment of bleeds to prevention, called prophylaxis. Although dosing and interval vary, prevention of joint disease is now a realistic goal. Unfortunately, despite advances in the safety of therapy, some patients are unable to use factor replacement products because they develop antibodies, known as inhibitors. Eradication of inhibitors is possible in the majority of patients, but it is expensive and takes time. Management of acute bleeding may require significantly higher doses of factor replacement or the use of a bypassing agent. As a result, patients with inhibitors are at increased risk for sequelae, including joint disease, life-threatening bleeding, infectious complications with central vascular access devices, and thrombotic complications.