BACKGROUND: In Taiwan, National Health Insurance (NHI) administration established Pharma Cloud System information since 2013. The purpose is to decrease therapeutic duplications and polypharmacy that enhance medication safety. OBJECTIVES: The study aimed reduced unnecessary medical costs and to analyze of characterize the data regarding the prevalence and types of out-patient drug-related problems(DRPs) after NHI PharmaCloud System was used. METHODS: The study included patients with therapeutic duplications and polypharmacy (≥5 drugs) at a medication therapy management service from January 2016 to October 2017. Patients in study group went to pharmacists in the pharmacy care unit for the on-line inquiries for prescription data in the NHI PharmaCloud System before they went to the OPD. DRPs were probed and recorded according to PCNE (Pharmaceutical Care Network Europe) Working group V8.02 on DRPs. RESULTS: Among them, suffering from diabetes, hypertension, hyperlipidemia patients’ whose medical expense up to 36.9 times per person. DRPs of incidence indication didn’t meet were 32%, drugs dose selection was 17% and drug recognition was 43%. The Number of drug items expense were 7.5 items. The total number of days in outpatient medical expense was 24 days, the drug cost average of 1252 NT dollars. The total number of days in outpatient medical expense decrease 2.7 days, the drug cost decreases average of 486 NT dollars. CONCLUSIONS: The study found that, the overlapped medical utilization increased as age, number of chronic conditions and number of the physicians visit increased. Application of PharmaCloud system, patient receiving pharmaceutical care before doctor visit demonstrated higher degree of satisfaction.