Idiopathic (immune) thrombocytopenic purpura (ITP) is an autoimmune disorder characterized by platelet destruction and thrombocytopenia (peripheral blood platelet count < 150 x 10^9/L). IVIG therapy is useful in patients in whom the platelet count has to be raised either due to bleeding signs, or where bleeding is predicted (e.g., surgery or parturition). The primary goal of treatment is to maintain the platelet count at a hemostatic level. This study will test the safety and efficacy of IGIV3I Grifols 10% in the treatment of patients with chronic ITP.