There are growing evidences on the role of adaptive mechanisms of all cell types in pathological processes: atherosclerosis, ischemic attack, bacterial infections, etc. All kinds of these processes involve as main mechanism oxidative stress. Aerobic organisms use oxygen in processes that accidentally or deliberately generate aggressive species for the biologic components in the form of radicals. Radicals were looked initially as “harmful” molecules and this is true for large quantities but in small or even moderate amounts these molecules prove to have a physiological role. Reactive species are highly reactive and as a consequence are short living species. Their impact is supposed to be limited in the proximity area of their formation. Instead recent evidences indicate their implications in cellular signaling suggesting that individual chemical properties of reactive species make a difference in their biological role. This paper presents superoxide, nitric oxide and peroxide radical generation under cellular changing conditions, the adapting behavior of the enzymes that synthesize and remove them as well as some therapeutic target in superoxide related pathology.