Post-rabies vaccine encephalomyelitis, postinfectious encephalomyelitis, and acute inflammatory demyelinating polyneuropathy are all monophasic, inflammatory, demyelinating diseases that appear to be autoimmune in pathogenesis and induced by prior antigenic stimulation or infection. The primary encephalitogen for rabies vaccine and postinfectious encephalomyelitis appears to be MBP, with a possible augmenting role for the myelin glycolipids. The primary neuritogen in AIDP may be a glycolipid, but this has not been clearly established. The mechanism by which a prior, apparently unrelated, stimulus leads to postinfectious encephalomyelitis or AIDP is unclear, but abnormalities of immune regulation, possible molecular mimicry between infectious agents and neural constituents, and genetic susceptibility may each play important roles (Table 1).