Recent evidence suggests that the pathogenesis of Sydenham's chorea following group A streptococcal infection is due to antibodies which develop due to the infection and infiltrate the brain and basal ganglia. Antibodies present in acute chorea react with the surface of neuronal cells and signal the induction of calcium calmodulin dependent protein kinase II with elevation of tyrosine hydroxylase and subsequent dopamine release which may lead to the movement disorder. The antibodies present in disease recognize lysoganglioside and the group A streptococcal epitope, N-acetyl-glucosamine. Monoclonal antibodies (mAbs) from Sydenham's chorea demonstrated the mimicry between lysoganglioside and the group A streptococcal carbohydrate epitope. A group of antibodies present in pediatric autoimmune neuropsychiatric disorders (PANDAS) were similar but not identical to the antibodies observed in chorea.