Patients meeting the enrollment criteria will be consecutively enrolled at each participating centre, randomized to be treated exclusively with a single FVIII product either plasma-derived or recombinant, and followed up until inhibitor development or until 50 exposure days (EDs) or 3 years from enrolment have elapsed, whichever comes first. Study products, belonging to the class of rFVIII concentrates and to the class of plasma-derived VWF/FVIII concentrates, will be provided for free to the patients for all the duration of the study