According to the accepted description, a tic is a psychogenic symptom, an expressive movement derived from a mental fixation. This concept was rejected by some of those authors who observed tic-like movements as sequelæ of acute encephalitis. Other cases, quoted by Steck (I), in which the onset of a hyperkinetic encephalitis was associated with tics, suggested still more definitely that there might be an organic cause for such movements. An extreme concept localized the lesion responsible for these symptoms in the corpus striatum. This wholesale assumption was in turn objected to from the neurological standpoint, particularly by Kinnier Wilson (2), who, in his well-known paper, pointed out how complicated the possible connections were. In particular he mentioned that even tics following encephalitis might be conditioned not only by the brain disease itself, but also by constitutional and psychic factors. The network of different ætiological factors becomes less complicated when a disease like chorea is studied, rather than cases of encephalitis where widespread permanent lesions remain. We have, therefore, studied the occurrence of tics in connection with chorea, though we do not claim that any conclusions can be drawn from these observations for tic neuroses generally.