Inhibitor of Factor VIII in Mild Haemophilia

Summary. Two patients with mild haemophilia developed inhibitors of Factor VIII during replacement therapy to cover major surgery. The inhibitors inactivated not only transfused antihaemophilic factor but also the patient's own Factor VIII and temporarily converted them to severe haemophiliacs. The activity of the inhibitors rapidly declined, possibly as a result of steroid therapy, and both patients eventually regained their previously mild haemophilic state.