The purpose of the study is to determine the efficacy, safety, and health-related quality of life benefits with FEIBA NF prophylactic treatment as compared with on-demand treatment. The study will be conducted globally and will consist of two arms. Eligible subjects will be randomized to undergo a 12-month period of either prophylactic or on-demand therapy.

• Hemophilia A
• Hemophilia B
• (High-titer) Factor VIII Inhibitor
• (High-titer) Factor IX Inhibitor

• Biological: Factor VIII Inhibitor Bypassing Activity (nanofiltered, vapor heat-treated)
  85 ± 15 U/kg of FEIBA NF every other day during the 12-month prophylactic period
  Other Name: FEIBA NF
• Biological: Factor VIII Inhibitor Bypassing Activity (nanofiltered, vapor heat-treated)
  Standard FEIBA NF dose and dosing interval as prescribed by the treating physician
  Other Name: FEIBA NF

• Prophylaxis arm: Experimental
  Intervention: Biological: Factor VIII Inhibitor Bypassing Activity (nanofiltered, vapor heat-treated)
• On-demand arm: Active Comparator
  Intervention: Biological: Factor VIII Inhibitor Bypassing Activity (nanofiltered, vapor heat-treated)

Inclusion Criteria:

• Signed and dated informed consent form by the subject or the subject's legally authorized representative
• The subject is >= 4 to <= 65 years of age
• The subject has a Karnofsky performance score of >= 60
• Hemophilia A and B of any severity, with documented history of high-titer inhibitor (> 5 BU) for at least 12 months; or, if inhibitor titer is <= 5 BU, and the subject is refractory with increased dosing of either FVIII or FIX, as demonstrated from the subject's medical history
• Currently being treated on an on-demand basis for treatment of bleeding episodes
• Adequate venous access, with or without central venous device
• >= 12 bleeding episodes requiring treatment with by-passing agents in the past 12 months, based on medical history
• Competent in-home treatment and infusion therapy
• Currently using bypassing agents (APCCs or rFVIIa) for treatment of bleeding episodes
• HCV-, either by antibody testing or PCR; or HCV+ with stable hepatic disease
• HIV-, or HIV+ with stable disease and CD4 count > 200 cells/mm3 at screening

Exclusion Criteria:

• Currently receiving immune tolerance induction (ITI)
• Currently on regular prophylactic therapy to prevent bleeding episodes
• Clinically symptomatic liver disease (e.g. diagnosis of cirrhosis [confirmed by liver biopsy], portal vein hypertension, ascites, prothrombin time (PT) 5 seconds above upper limit of normal)
• Platelet count < 100,000/ml
• Planned elective surgery during participation in this study
• Subject is currently participating in another clinical study and has received an investigational product or device within 30 days prior to study entry
• Planned use of pegylated or non-pegylated alpha-interferon with or without ribavirin for HCV infected subjects or planned use of a protease inhibitor for HIV infected subjects. Subjects currently taking any of these medications for a 30-day course are eligible.
• D-dimer levels twice the upper level of normal
• Known hypersensitivity to AICCs
• Currently treated with a systemic immunomodulating drug
• Prior history of thromboembolic event: acute myocardial infarction, deep vein thrombosis, or pulmonary embolism
• Diagnosis of advanced atherosclerosis, malignancy and/or other diseases that may increase the subject's risk of thromboembolic complications
• Clinically significant medical, psychiatric, or cognitive illness, or recreational drug/alcohol use that, in the opinion of the investigator, would affect subject safety or compliance