The form of coenzyme Q in humans, CoQ10, containing a benzene ring linked to a 10 units isoprene tail, plays many essential roles in biochemistry, metabolism and physiology in our organisms. Being the only lipidic member of the mitochondrial electron transport chain it also plays other essential catabolic and anabolic functions by transferring electrons. One of these functions is to act as antioxidant in all the cell membranes and in plasma lipoproteins. In this chapter the importance of maintaining CoQ10 levels during aging is highlighted by the studies that have demonstrated a protective role of cells, tissues and organs against the deterioration associated with aging and age-related diseases. The protective effect can be in part due to prevention of endothelial dysfunction that has been associated with many of the age-related diseases and with the process of aging. The supplementation of CoQ10 in elderly people is recommended in the base of many studies indicating its safety and its role as antioxidant and essential compound in mitochondrial function.