The orphan drug pimozide was recently approved for marketing in the U.S. for the treatment of Tourette's syndrome (TS). TS is characterized by recurrent, involuntary motor movements and vocal tics, and is believed to be due to neurochemical dysfunction. Pimozide's receptor selectivity differs from that of haloperidol, the standard agent used for TS. Clinical trials with pimozide demonstrate a positive response for many patients, although superiority over haloperidol has not been demonstrated in general. Pimozide causes annoying side effects in a large percentage of patients and may cause severe side effects (e.g., tardive dyskinesia, cardiovascular toxicity) with prolonged use and/or at higher doses. The long half-life of pimozide allows for once-daily dosing. Pimozide should be reserved for treatment of patients with TS who have not responded to haloperidol or who cannot tolerate haloperidol's adverse effects.