The authors performed a prospective study to correlate echocardiographic left ventricular hypertrophy (LVH) and silent ischemia (SI) detected by twenty-four-hour ambulatory electrocardiographic monitoring with new cardiac events in 355 patients, mean age eighty-two ± eight years, with systemic hypertension or coronary artery disease (CAD). Cardiac events included myocardial infarction, primary ventricular fibrillation, or sudden cardiac death. Mean follow-up was thirty-one ± seven months (range twelve to forty). Cardiac events occurred in 28 of 147 patients (19%) without LVH or SI (A), in 56 of 113 patients (50%) with LVH and no SI (B), in 16 of 29 patients (55%) with SI and no LVH (C), and in 52 of 66 patients (79%) with LVH and SI (D). Significant p values were p < 0.001 comparing D with A, D with B, C with A, and B with A; and p < 0.02 comparing D with C. These data indicate that echocardiographic LVH and SI detected by ambulatory electrocardiographic monitoring are independent risk factors for new cardiac events in elderly patients with systemic hypertension or CAD.