OBJECTIVES: Medication reconciliation is the process to compare patients’ existing and previous medication regimens to identify and avoid medication errors. All medications should be appropriately and consciously continued, discontinued, or modified at all transitions of care. The objective of this study is to implement medication reconciliation at admission to reduce drug-related problems and to evaluate the financial impact of these approaches in Taiwan. METHODS: The patients admitted to the local hospital and stayed more than three days were recruited in this study, while the patients with cancer or admitted to the ICU were excluded. Next, pharmacists reviewed the charts of admitted patients and compared the medication regimens at present and before admission. Once the unreconciled medications were identified, pharmacists would discuss with the physicians to ensure if therapy should be adjusted. The determination of financial impact is expressed by cost avoidance per year in Taiwan. RESULTS: The data from our study suggests that between 5% and 10% of drug-related problems were identified and prevented by pharmacists through the process of medication reconciliation. This can translate into between 158,400 and 316,800 episodes per year in Taiwan (based on the assumption for total hospitalization of about 3,168,000 persons per year). The estimated cost avoidance will be as high as NT 792 million to 1584 million per year (based on the assumption that cost of prolonged length of hospital stay is about NT 5000) through executing the medication reconciliation at admission. CONCLUSIONS: This study demonstrated that the pharmacists' interventions were able to prevent potential adverse drug events and reconcile discrepancies among medication, as well as reduce medical expenditure. Effective assurance in medication safety is achieved through the collaboration of patient care team.