Electrocardiographic (ECG) abnormalities are common in hypertrophic cardiomyopathy (HC) and have been associated with the distribution of left ventricular hypertrophy and myocardial fibrosis. Such abnormalities may predispose patients to electrophysiologic instability, ventricular arrhythmias, and sudden cardiac death (SCD). We studied 330 patients with HC who were judged clinically to be at high risk for SCD and therefore received automatic implantable cardioverter-defibrillators (ICDs). Surface 12-lead electrocardiograms acquired at the time of ICD implantation were analyzed and the ECG characteristics of patients with appropriate device interventions for ventricular tachycardia and fibrillation were compared to those patients without appropriate device interventions. The 330 patients were followed for 3.7 ± 3.0 years after implantation and 57 patients (17%) had appropriate discharges. No differences in the ECG characteristics of patients with and without appropriate device interventions were identified. Markedly increased ECG voltages, QRS duration, left or rightward QRS axis, abnormal Q waves, and QTc or QT dispersion were not associated with appropriate ICD discharge. Conversely, normal electrocardiograms and electrocardiograms normal except for a repolarization abnormality in only 1 anatomic distribution were not associated with freedom from ICD discharge. Moreover, no combination of ECG variables was associated with the likelihood of an appropriate ICD discharge. In conclusion, in a cohort of patients with HC selected because of their high risk for SCD, 12-lead surface electrocardiogram did not predict subsequent appropriate ICD intervention for ventricular tachyarrhythmias and was not useful in risk stratification for sudden death.