We report the successful treatment of a 59-year-old woman with acquired factor VIII inhibitor. The patient who had an extensive leg hematoma with a resultant neurologic defect was treated with extracorporeal immunoadsorption (IA) using protein A-Sepharose, factor VIII concentrates, azathioprine, and methyl-prednisolone. Extracorporeal IA reduced the titers of the inhibitor so that factor VIII concentrates could raise the level of factor VIII coagulant activity and stop the bleeding.