A case of acquired FVIII inhibitor in a nonhemophilic, 80 year-old man who had no underlying disorder, is presented. The level of inhibitor was 13.3 Bethesda unit/ml, and the antibody was IgG, with λ light chain. The antibody reacted with the 92kD fragment of non-treated human FVIII, and the 44kD fragment of thrombin treated FVIII when analysed by the immunoblot analysis.
