A 51 year-old woman with severe thrombocytopenia, hemolytic anemia, renal failure and loss of consciousness, and significant decrease in plasma large multimer of von Willebrand Factor (vWF) was diagnosed as having thrombotic thrombocytopenic purpura (TTP). She was treated with plasma exchange, anti-platelet agents and steroids. Although she showed temporary improvement and return of vWF multimer to a normal level, her symptoms reappeared, vWF large multimer level showed a remarkable increase, and she died because of pulmonary bleeding. It would be important that the vWF multimer bands changed in the course of TTP.