Clozapine (Clozaril) represents the first major advance in the pharmacological treatment of schizophrenia since the introduction of antipsychotics into clinical practice in the 1950s. Studies consistently support its efficacy for reducing positive symptoms in acutely psychotic patients and in treatment-resistant patients, for preventing positive symptom exacerbations as a maintenance treatment, and for reducing symptoms of hostility and violence. There is evidence to suggest that clozapine may improve social and occupational functioning and quality of life and may reduce affective symptoms, hospitalizations, secondary negative symptoms, and tardive dyskinesia. Its most significant side effects include agranulocytosis, seizures, weight gain, hypotension and tachycardia, sedation, and perhaps rebound psychosis (with abrupt discontinuation of medication).