Elderly patients are particularly vulnerable to adverse drug events in both the ambulatory and inpatient settings. This study evaluated the effect of integrating clinical pharmacists into medical teams caring for geriatric patients, a strategy that has been demonstrated to reduce medication errors in prior research. The pharmacists in this study carried out medication reconciliation and education during the hospitalization and communicated specific medication information to patients' outpatient physicians at discharge. This intervention proved effective at reducing readmissions and medication-related emergency department visits and was cost effective. The interventions carried out by the pharmacists in this study, particularly at the time of discharge, are similar to those performed by nurses in prior studies that successfully reduced hospital readmissions.