Edited by Ruth H. Walker, MB, ChB, PhD The involuntary movement disorder known as chorea can be due to a wide variety of neurological conditions, both genetic and acquired. This volume provides a comprehensive account of these conditions. While Huntington's disease is the prototypic inherited chorea, with the development of the genetic test for this disorder it has become apparent that a small but significant proportion of patients with this phenotype do not have this diagnosis. Although less common than Huntington's disease, it is vital to correctly diagnose these patients with advances in molecular medicine, it is now easier to identify new genetic causes of chorea and expand the phenotype of disorders not typically thought to cause this movement disorder. Non-genetic etiologies are also discussed, including medications, structural lesions, psychogenic causes, and metabolic abnormalities.