A variety of neurotransmitters have been implicated in the pathophysiology of chorea as exemplified by Huntington's chorea. These include dopamine, serotonin, acetylcholine, GABA and a variety of neuropeptides including substance P and somatostatin. Despite biochemical data that suggests that alterations in other neurotransmitters may be of greater significance, pharmacologic data still supports a major role of dopamine in the actual clinical manifestation of chorea.