Study Evaluating ReFacto AF in Severe Hemophilia A

Inclusion Criteria: * Severe hemophilia A (FVIII:C less than or equal to 2% at local laboratory) * Previously treated patients with greater than or equal to 250 exposure days to any Factor VIII product * Age greater than or equal to 12 years * History of prophylaxis dosing at least twice per week on any Factor VIII product for at least 3 consecutive months within the 2 years prior to study enrollment unless the patient completed the previous pharmacokinetic study * Adequate laboratory results Exclusion Criteria: * Presence of any bleeding disorder in addition to hemophilia A * Concomitant therapy with immunosuppressive drugs * Current or historical Factor VIII inhibitor * Treatment with any investigational drug or device within the past 30 days