In this review some aspects of free radical theory of aging are discussed. Many new and interesting findings concerning the role of physiological free radicals superoxide and nitric oxide in senescence and aging development are considered and the mechanisms of processes mediated by these radicals are discussed. It has been known for a long time that being themselves mostly harmless species, superoxide and NO are precursors of really reactive species hydroxyl radicals and peroxynitrite, the initiators of aging and various pathologies. However, contemporary studies demonstrate the other maybe more important ways of damaging activity of physiological free radicals. Numerous studies show that lessening of NO production and its bioavailability could be a starting point of aging development. It results in a decrease in NO inhibition of mitochondrial cytochrome c oxidase and an increase in dioxygen consumption. That in its turn leads to an increase in the production of superoxide and the other reactive oxygen and nitrogen species and initiation of apoptosis, In conclusion the possibilities of pharmacological intervention with antioxidants and other antiradical procedures to suppress aging and senescence or even to expand the life span of animals are considered.