The risk of various diseases increases with age. As “powerhouses of the cell”, mitochondria are of particular importance for the prevention and therapy of age-related diseases. Adenosine triphosphate (ATP) is the universal energy currency of the cell. Via oxidative phosphorylation, the energy production with oxygen consumption, more than 90% of the energy of the organism is generated in the form of ATP in the mitochondria. Reactive oxygen compounds, so-called “free radicals”, are formed as a by-product of aerobic energy generation. Free radicals can react with and damage mitochondrial and cellular membrane and protein structures. Radical-induced damage is associated with various ageing processes. Coenzyme Q10 is a fatsoluble antioxidant that accumulates in membrane structures. In the mitochondria it serves as an electron and proton carrier between the respiratory chain proteins. As it supports mitochondrial function and is able to neutralize free radicals directly at their place of origin, coenzyme Q10 is a promising anti-ageing supplement.