Initially used as replacement therapy in patients with hypogammaglob-ulinemia, intravenous gamma-globulin (IVIg) preparations are increasingly being used as treatment for various autoimmune disorders. Although expensive, IVIg has become first-line or adjunctive therapy in the treatment of disorders as diverse as autoimmune or post-transfusion thrombocytopenia, autoimmune hemolytic anemia, Kawasaki's disease, inflammatory myositis, myasthenia gravis, pediatric acquired immune deficiency syndrome, bone marrow transplantation, and inflammatory de-myelinating polyneuropathy. IVIg remains the first line of therapy in patients with humoral immunodeficiency syndromes. Clinical studies support the selective use of this therapy in the above disorders; it has also been tried as therapy in many other diseases, with varied results. IVIg therapy has received Food and Drug Administration approval for use as maintenance treatment of patients with primary humoral immunodeficiencies and as therapy for acute or chronic autoimmune thrombocytopenic purpura.