**Abstract**

Antipsychotics polypharmacy is commonly used in treatment of schizophrenia, despite a lack of evidence to support its safety and efficacy. Antipsychotics polypharmacy often results in high dose prescribing, additional adverse effect, difficulty identifying the drug that resulted in adverse effect, and relatively high cost compared to antipsychotics monotherapy. This study investigated the prevalence of antipsychotics polypharmacy and related clinical characteristics among schizophrenia patients who admitted to national mental hospital. Data of demographic characteristics, length of hospital stay, and prescribed antipsychotics was collected retrospectively using electronic medical record for inpatients with diagnosis of schizophrenia or schizoaffective disorder who discharged from National Chuncheon Hospital from 1st April 2011 to 30th 2013. Among 794 patients, antipsychotics polypharmacy was found in 500(63.8%) patients. Among these, 384(76.8%) patients were prescribed two kinds of antipsychotics, 98(19.6%) with three, 17(3.4%) with four, and 1(0.2%) with five, respectively. Clozapine was prescribed in 152(19.4%) patients. In patients with antipsychotics polypharmacy, quetiapine was most frequently prescribed antipsychotics(242 cases), followed by risperidone(171 cases). Length of hospital stay was significantly longer in patients with antipsychotics polypharmacy than patients with antipsychotics monotherapy. In this preliminary study, higher rate of antipsychotics polypharmacy than suggested in previous studies was found in patients with schizophrenia in national mental hospital. Further study is needed to clarify the reasons and the impact of predominant use of antipsychotics polypharmacy in national mental hospitals.

***Keywords:** schizophrenia, antipsychotics polypharmacy, national mental hospital*
