Tourette's syndrome, or Gilles de la Tourette's disease, is a disorder characterized by involuntary tic-like muscular movements, compulsive behaviour and involuntary vocalization of sounds, words or profanities. It begins in childhood and may persist for life, with a varied pattern and course. Recent studies indicate an organic basis for the disorder, and an abnormality of dopamine or purine metabolism has been suggested. The treatment of choice is haloperidol administration; most patients do well with low or moderate doses for long periods. Because these patients are often mistakenly regarded as anxious, psychoneurotic or hysterical, correct diagnosis is important if they are to be treated appropriately and regarded properly in the home, school and society.