Antibody responses to myelin antigens were analysed in 15 patients who developed acute neuroparalytic accidents (ANPA) during post-exposure rabies vaccination using a rabies vaccine prepared on brain tissues and in 30 individuals who were uneventfully vaccinated. High titers (> or = 100) of IgG and IgM antibodies to GM1 or GD1a gangliosides were detected by enzyme linked immunosorbent-assay (ELISA) in plasmas from ANPA patients but not in controls. These data suggest that antibodies to GM1 and GD1a gangliosides may play a pathogenic role in the demyelinating and/or inflammatory processes characteristic of rabies vaccine-induced acute neurologic complications.