Frailty is a progressive physiologic decline in multiple body systems marked by loss of function, loss of physiologic reserve, and increased vulnerability to disease and death. Until recently, frailty has been poorly defined in the medical literature. One currently accepted definition of frailty is having 3 of the following 5 attributes: unintentional weight loss, muscle weakness, slow walking speed, easy exhaustion, and low physical activity. The mechanisms that underline frailty remain unclear. Significantly higher levels of markers of inflammation and the clotting cascade have been found in frail persons compared with nonfrail persons. These markers are also risk factors for the development of coronary heart disease. Recent research has indicated that frailty is a clinical manifestation of cardiovascular disease, especially of heart failure. Thus, understanding the connection between frailty and cardiovascular disease may lead to development of new interventions that will prevent and reverse the associated morbidity and mortality.