PROJECT SUMMARY/ABSTRACT Aging is one of the greatest risk factors for the development of cardiovascular disease and heart failure. Mitochondrial dysfunction in the aging heart is thought to be an important contributing factor to the decline in cardiovascular function with age, including hypertrophy and left ventricular wall thickness, diastolic dysfunction, and reduced contractility and calcium dynamics that contribute to the increased risk for clinically important cardiovascular disease. Despite the growing interest in the mitochondrial biology of aging and the clear clinical and