Immunoglobulins, used at first empirically in the treatment of thrombocytopenic purpura, occupy a prominent place not only in the treatment of antibody deficiencies, but also in that of antoimmune diseases. Their indications in neurology are ever extending; they include myasthenia, chronic inflammatory polyneuropathies with or without monoclonal gammopathy, polymyositis, dermatomyositis and, more recently, disseminated sclerosis and Guillain-Barré syndrome. Even the therapeutic priority of plasmapheresis in this syndrome is disputed by some authors. Immunoglobulins are costly, but they are well tolerated and easy to use. Their effectiveness must be confirmed by controlled, double-blind trials. In neurology such trials are still rare, but those recently published are devoid of methodological errors. Once the effectiveness of immunoglobulins is confirmed, their dosage must be established, and attempts should be made at a better understanding of their mechanisms of action.