Medication reconciliation is a practice for identifying discrepancies in drug managements prescribed in care settings to inform prescribing decisions and prevent medication errors. Recognition and management of medication discrepancies to reduce Adverse Drug Effects are a major focus of patient safety efforts. As a fragment of the National Patient Safety Goals program, the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) allotted a mandate requiring hospitals to perform medication reconciliation at each transition of care. At basic level, most organizations agree that a medication reconciliation includes a best possible medication history that is reconciled with the medications prescribed. Canadian health care providers have invested billions of dollars in hospital-based Emergency Medication Reconciliation with the intention of improving hospital efficiency and patient outcomes. Integrated medication reconciliation led by a hospital clinical pharmacist in collaboration with all health professionals involved in the patient's pharmacotherapy and treatment, significantly reduced unintended discrepancies in the transfer of care. The implementation of pharmacist-led medication reconciliation service had a positive clinical and economic impact in hospital.