DDAVP (1-deamino 8 D-arginine vasopressin) was administered on two occasions to a patient with an acquired factor VIII inhibitor. Because the patient's autoantibody was low titre (1.8 Bethesda units) and had type II kinetic properties, it was expected that endogenous factor VIII/VWF released by DDAVP would be inactivated at a slow enough rate to permit satisfactory haemostasis during dental procedures. In both instances there was a 7-9-fold increase in factor VIII above the baseline level (13 units/dl), and factor VIII activity remained above 35 units/dl for 5 h after the infusion. The inhibitor could not be detected in his plasma during this period and the activated PTT was shortened into the normal range. Our experience with this patient suggests that DDAVP has a role in the management of some patients with low titre autoantibodies that inactivate factor VIII.