Molecular mimicry of microbial components by self components is thought to be the mechanism that accounts for the antigen and tissue specificity of immune responses in post-infectious autoimmune diseases. Little direct evidence exists, and research in this area has focused principally on T cell mediated anti-peptide responses, rather than on humoral responses to carbohydrate structures. Guillain-Barré syndrome, the most frequent cause of acute neuromuscular paralysis, sometimes occurs after Campylobacter jejuni enteritis. Recent studies have revealed that carbohydrate mimicry of the bacterial lipo-oligosaccharide by the human ganglioside is an important cause of the syndrome. This new concept that carbohydrate mimicry can cause an autoimmune disease provides a clue to inducing the resolution of pathogenesis of other immune-mediated diseases.