Individualized lot selection will be performed according to a modified Oxford method in a central laboratory, by testing subject's plasma against 4-6 lots of Wilate® and selecting the one with the highest residual FVIII (lowest Oxford titer) activity remaining after incubation. The same lot will be used throughout the entire ITI course for each subject. If the selected lot is depleted prior to the completion of ITI, a second individualized lot selection will be performed using the original plasma sample provided at baseline.