BACKGROUND:The study aimed to determine the frequency of enoxaparin dosing errors for patients who had a measured emergency department (ED) weight compared to those who did not have a measured ED weight, and to determine if demographic variables (e.g., weight, height, age, English-speaking, race) impact the likelihood of receiving an inappropriate dose. METHODS:This is a retrospective, electronic chart review of patients who received a dose of enoxaparin in the ED between January 1, 2008 and July 1, 2013. We identified all patients >18 years who received a dose of enoxaparin while in the ED, were admitted, and had at least one inpatient weight within the first four days of hospitalization. Patients were excluded if they received enoxaparin for prophylaxis or a dose of more than 1.25 mg/kg. RESULTS:A total of 1,944 patients were included. Patients were more likely to experience an error if they did not have a measured ED weight. Over-doses of >10 mg were more likely to occur in patients without a measured ED weight. Patients with no documented ED weight or with a staff-estimated ED weight were more likely to experience a dosing error than those with a patient-stated weight. Patients were more likely to experience an error if their first inpatient weight was more than 96 kg, they were more than 175-cm tall, or were English speaking. CONCLUSION:Dosing errors are more likely to occur when patients are not weighed in the ED. Modifications to current workflows to incorporate weighing those patients who receive weight-dosed medications may be warranted.