Background : The elderly population is rapidly increasing in Korea. The issue of polypharmacy has become one of the main problems in geriatric care due to the high prevalence of chronic disease in older persons. In this study, we investigated the current status of inappropriate multiple drug prescriptions in retired police officers aged ≥ 65 years, who were scheduled from March to April in 2015. This was a retrospective study to survey the prevalence of potentially inappropriate medications (PIMs) used for elderly patients. Selection of PIMs was based on the Beers/STOPP criteria and additional proposal. We researched the medication profiles of a total of 358 geriatric patients, who were scheduled in outpatient department at National Police Hospital during the period of the 1st of March to the 30st of April of 2015. The objective of this study was to confirm the intervention role of pharmacists in elderly patients, and determine further usefulness of the Comprehensive Geriatric Assessment in the extension of the role of pharmacists in the alteration of prescription. Methods : We included 358 elderly patients older than 65 years who visited the outpatients' clinic from March 1st 2015 to April 30th 2015. Comprehensive geriatric assessments, drug-drug interaction, creatinine clearance, overlapping prescription of similar efficacy, including medication review by the pharmacists were performed. Beers/STOPP criteria and additional proposal were used to determine PIMs. Statistical analysis was performed using the Pearson’s Chi-square test version 11.0(SPSS). A p-value of <0.05 was considered statistically significant. Results : A total of 179 cases (50%) by Beers criteria and 80 cases (22.3%) by additional proposal were prescribed with PIMs. After the intervention of pharmacists, the percentage of the patients who received inappropriate medication by Beers criteria decreased by 28.4% (102 cases). According to increasing numbers of diagnoses, increases were observed for a total number of medicines per patient (<0.003), the risk of inappropriate prescription by Beers/STOPP criteria (<0.001), the risk of adverse drug reaction (<0.001) and a total number of medicines to be considered for renal function (p<0.001). Increasing the total number of medicines per patient was correlated with the risk of inappropriate prescription by Beers/STOPP criteria (<0.001), the risk of adverse drug reaction (<0.003), a total number of medicines to be considered for renal function (p<0.001) and prescription of anticoagulant, antithrombotic and antiplatelet agents (<0.001). Conclusion : A considerable number of cases of prescriptions likely to cause adverse events in older patients were identified. Our study raised the alert for harmful effects of polypharmacy and the necessity of well-structured drug monitoring system for older persons. The intervention of pharmacists in this study was associated with significant reductions in inappropriate prescribing. Our results demonstrated that the medication assessment of pharmacists leads to safer and more appropriate pharmacotherapy for elderly patients. Therefore, the intervention of pharmacists in older patients should be considered to reduce incidences that are related to the pharmacotherapy and the extension of the role of pharmacists for the prescription process.