Psychotic symptoms, including hallucinations, delusions, delirium, sleep disturbances, are a common problem associated with movement disorders. For instance, psychosis as one of the most disabling levodopa-induced complication occurs in up to 30% of patients with Parkinson's disease (PD). The prevalence of psychotic symptoms in Huntington's disease (HD) ranges from 3.4–30%, while only schizophrenia-like expression was noted in 9% of HD patients. Psychosis can be more disabling than the motor symptoms in patients with movement disorders: it seriously influence the patient's ability to maintain independence and is among the greatest risk factors for nursing home placement. The conventional antipsychotics are poorly tolerated in patients with movement disorders, and in particular in PD patients, since they can induce profound worsening or appearance of parkinsonism and tardive symptoms. The atypical antipsychotic drugs (ie, clozapine, olanzapine, quetiapine, risperidone, etc.) offer improved therapeutic strategy that control psychotic symptoms without compromising motor function