Abstract: A neurobehavioral disorder that is characterized by frequent, recurrent motor and vocal tics (described in 1885 by the French neurologist Gilles de la Tourette). The motor tics of Tourette's syndrome include brief, rapid, and darting movements of almost any muscle group, and can include eye blinking, eye rolling or deviations, nose wrinkling, facial grimacing, and head shaking. Some motor tics are more complex, are slow, and appear purposeful such as head turning, shoulder shrugging, touching, hopping, or twirling. Vocal tics are brief guttural sounds such as recurrent sniffing, throat clearing, coughing, and grunting or barking sounds. Complex vocal tics can be more meaningful and include expressions such as ?No,? ?Stop,? or ?Some other time.? Infrequently, persons with Tourette's syndrome repeat what they have said (palilalia), repeat what others have said (echolalia), or bark or grunt profane language (coprolalia). Tourette's syndrome has been described in nearly every country and ethnic group, with an estimated prevalence of one or two occurrences per 2000 people