Medication errors are frequent in the emergency department (ED). The unique operating characteristics of the ED may exacerbate their rate and severity. They are associated with variable clinical outcomes that range from inconsequential to death. Fifteen adult and pediatric cases are described here to illustrate a variety of errors. They may occur at any of the previously described five stages, from ordering a medication to its delivery. A sixth stage has been added to emphasize the final part of the medication administration process in the ED, drawing attention to considerations that should be made for patients being discharged home. The capability for dispensing medication, without surveillance by a pharmacist, provides an error-producing condition to which physicians and nurses should be especially vigilant. Except in very limited and defined situations, physicians should not administer medications. Adherence to defined roles would reduce the team communication errors that are a common theme in the cases described here.