Such neuropathies as Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyneuropathy (CIDP), and IgM paraproteinemic neuropathy are caused by autoimmune mechanisms. IgM paraproteinemic neuropathies are known to be intractable. Rituximab has recently been reported to be effective for IgM paraproteinemic neuropathy with anti-MAG IgM M-protein in a placebo-controlled trial. The effect should be confirmed with a larger trial. The use of this drug also may be tried for other type of IgM paraproteinemic neuropathy and for intractable CIDP in future. Antiganglioside IgG antibodies are frequently present in the acute-phase sera from GBS patients. Recently, presence of the antibodies that recognize a conformational epitope formed by carbohydrate portions of two different gangliosides (ganglioside complex) has been reported. Antibodies against a complex formed by GD1a and GD1b (anti-GD1a/GD1b antibodies) are associated with severe GBS. Anti-GM1/GalNAc-GD1a antibodies are found to be associated with pure motor GBS with frequent conduction block. Anti-ganglioside complex antibodies may be useful diagnostic and prognostic markers of GBS. Future study is necessary to clarify the pathogenetic mechanisms in which those antibodies are specifically involved.