Hemophilia A is an inherited blood disorder in which one protein, Factor VIII, needed to form blood clots is missing or not present in sufficient levels. Hemophilia A causes the clotting process to be slowed and the person experiences bleeds causing serious problems that could lead to disability. The current standard treatment for severe hemophilia A is infusion of FVIII to stop bleeding, or regular scheduled treatment to prevent bleeds from occuring. Due to the short half-life of FVIII, prophylaxis may require treatment as often as every other day.

In this trial safety and efficacy of a long-acting recombinant Factor VIII molecule is being evaluated in 50 male subjects, < 12 years of age, with severe Hemophilia A. These subjects will receive open label treatment with long-acting rFVIII for approximately 6 months (or longer until 50 exposure days) on a regular schedule at least once every 7-days. Doses and dose intervals may be adapted to the subject's clinical need. A second group of patients will receive open label treatment with the same drug for 12 weeks on a regular schedule of 2x/week. Patients will attend the treatment center for routine blood samples and will be required to keep an electronic diary.

Subjects will be offered participation in an optional extension study to collect observations for at least an additional 50 exposure days.

Inclusion Criteria:

• Males < 12 years of age
• Subjects with severe hemophilia A
• Previously treated with FVIII for > 50 exposure days

Exclusion Criteria:

• Subjects with current evidence of or history of inhibitors to FVIII
• Any other inherited or acquired bleeding disorder
• Platelet counts < 100,000/mm^3
• Creatinine > 2x the upper limit of normal
• Aspartate aminotransferase (AST) / Alanine aminotransferase (ALT) > 5x the upper limit of normal