The electrocardiogram's (ECG) ability to aid in the diagnosis and risk stratification of patients with acute coronary syndromes is well established. We sought to investigate the prognostic significance of ECG abnormalities in patients with noncardiac conditions in the emergency department. Patients presenting to the emergency department who were evaluated for possible acute coronary syndrome were consecutively enrolled and an initial ECG was obtained (n = 1024). Only patients with noncardiac diagnoses were reviewed in this analysis (n=493) and 30-month follow-up was obtained. Sinus tachycardia, atrial fibrillation/flutter, ST depression, and left bundle branch block were associated with increased 30-month mortality. After controlling for history of coronary artery disease, age, sex, diabetes mellitus, hypertension, and renal insufficiency, sinus tachycardia and ST-segment depression ≥1 mm were independent predictors of 30-month mortality with a hazard ratio of 2.33 (95% confidence interval, 1.36-4.00; P = 0.002) and 2.49 (95% confidence interval, 1.10-5.67; P = 0.029), respectively. In conclusion, ST-segment depression and sinus tachycardia in patients presenting to the hospital with noncardiac conditions are independently associated with increased 30-month mortality.