Acquired von Willebrand syndrome has been reported in patients with a variety of primary diseases, many immunologic in nature. Usually, an autoantibody to von Willebrand factor can be identified. These patients often experience severe hemorrhages requiring large doses of cryoprecipitate or factor VIII concentrates, thus exposing them to viral and allergic complications. The success of intravenous gamma-globulin in the treatment of other autoimmune diseases prompted us to treat two patients with acquired von Willebrand syndrome with high-dose intravenous gamma-globulin. Two days after initiation of therapy, von Willebrand factor and factor VIII rose to normal levels in both patients. Patient 1 underwent dental surgery, and patient 2 underwent a splenectomy without increased bleeding and without additional factor coverage or desmopressin acetate therapy. Thus, intravenous gamma-globulin is efficacious for acquired von Willebrand syndrome and obviates the need for replacement therapy with its attendant complications.