['We investigated the localization of a ganglioside, N-acetylgalactosaminyl GD1a (GalNAc-GD1a), in peripheral nerves with an IgG anti-GalNAc-GD1a antibody, which was produced in rabbits immunized with GalNAc-GD1a.', 'Teased fibers from ventral and dorsal roots and hemidiaphragm sections of rats were assessed using fluorescent double- and triple-labeling methods.', 'The nodal and paranodal regions of teased fibers from ventral roots were immunostained with IgG anti-GalNAc-GD1a antibodies. After collagenase treatment, no staining was seen with IgG anti-GalNAc-GD1a or anti-NF200 antibodies, whereas α-bungarotoxin selectively stained nerve terminals. In cross-sectional and longitudinal sections of rat hemidiaphragm, IgG anti-GalNAc-GD1a antibodies overlapped with α-BuTx and anti-NF200 antibodies, indicating that GalNAc-GD1a is localized to the nerve terminal. IgG anti-GalNAc-GD1a antibody staining also overlapped with that of AChR clusters and syntaxin-positive presynaptic nerve terminals.'] Do igG anti-Galnac-GD1a antibodies bind to neuromuscular junctions of rat hemidiaphragm?