The Hakodate Watanabe Hospital has held pharmacist-led multidisciplinary psychiatric pharmacotherapy conferences since September 2013 in order to optimize pharmacotherapy. The effects of holding regular conferences on the correction of high-dose antipsychotic polypharmacy, prevention and reduction of adverse reactions to antipsychotics, and reduction of the drug costs were investigated in psychiatric inpatients prescribed 4 or more antipsychotics. The results revealed that the number of antipsychotics and number of all drugs were significantly reduced by 1, the chlorpromazine (CP)-equivalent dose was significantly reduced by approximately 350 mg, and the drug costs were significantly reduced by 176.5 yen/d. In regard to the effects on the laboratory test data, the blood glucose and hemoglobin Alc (HbAlc) levels were significantly reduced. In addition, 84.8% of the patients were assessed as "unchanged" using the Clinical Global Impression of Change (CGI-C), indicating the absence of any significant changes in the severity of the clinical psychiatric symptoms. The results confirm that psychiatric pharmacotherapy conferences are effective for promoting appropriate use of antipsychotics, reducing the incidence of metabolic adverse reactions, such as elevation of the blood glucose, and also reducing the drug costs. The above results suggest that psychiatric pharmacotherapy conferences encourage psychiatric medical teams to adjust prescriptions while sharing information, and are effective for optimizing pharmacotherapy.