Patients hospitalized with acute coronary syndromes or strokes are particularly vulnerable to medication errors, as many of these patients are elderly, have complex medication regimens, or are administered high-risk medications such as anticoagulants. This position paper from the American Heart Association reviews the specific types of medication errors in these patients, including dosing errors, administration of contraindicated medications, and errors of omission (failure to prescribe recommended therapies). The authors make specific, evidence-based recommendations for preventing medication errors in this patient population, including integrating pharmacists into inpatient teams and using computerized provider order entry and medication reconciliation to detect and prevent errors. A medication error in an acute coronary syndrome patient is illustrated in this AHRQ WebM&M commentary.