There is conflicting evidence with regard to the value of electrocardiographic left ventricular hypertrophy (LVH) in myocardial infarction. Of 5,951 patients in the ASSENT-3 trial, 273 (5%) had LVH on baseline electrocardiograms and had significantly higher mortality rates at 30 days (11% vs 6%, p = 0.001) and 1 year (13% vs 8%, p = 0.007). After adjustment for differences in baseline parameters, LVH remained an independent predictor of 30-day (hazard ratio 2.3, 95% confidence interval 1.4 to 3.9) and 1-year (hazard ratio 1.8, 95% confidence interval 1.1 to 2.8) mortality rates. Thus, electrocardiographic LVH is a prognostic tool in identifying short- and long-term mortality rates in patients who have ST-elevation myocardial infarction and receive fibrinolysis.