In this essay the introduction is built of prepositions about the reactions in prebiotic atmosphere that lead to appearance of first carbohydrates, nucleotides and amino acids that are building blocks and information containing molecules for every known life form. That gave birth for first live organisms such as viruses and bacteria’s. Most of them where chemotrophic and organotrophic and anaerobic. By the evolution pathway phototrophic organisms appeared and began to use the solar power to transform it in energy of chemical reaction with help of chlorophyll. In this moment the history of oxygen begins. The atmosphere began to form. With the appearance of the ozone layer climatic conditions on Earth became more friendly and mild. In this period evolution gave birth to aerobicorganisms that use oxygen for breathing and oxidizing carbohydrates to gain energy for chemical reaction. As well in this essay is described the anaerobic pathway of breathing and oxidizing the glucose. Oxygen in multicellular organisms is transported with special molecules a little bit similar to chlorophyll as hemoglobin (that gives it a red color) for mammals, hemocianin (blue color) for clams, chlorocruorin (yellow color) for snakes and hemeritrin that is violet and found in other type of invertebrates. What is most of all amasing in oxygen, that it as well kills us while sustains our lives. More precisely oxygen’s harmful species that are a lot more oxidative agents. It can be a cause of a broad diversity of illnesses such as mutagenesis, atherosclerosis, arteriosclerosis, chronical inflammation processes, cancer, heart attack, cataract and different problems with central nervous system. The common dangerous species of oxygen that appear in organism as side reaction products are superoxide, hydrogen peroxide and hydroxyl radical. As for any harmful process organism tries to detoxify this species with help of antyoxidative ferments such as glutathione peroxidase, as well in nature are a lot of substances that can play such a role. For example, vitamin E, C, Ferritin, B-carotene, Glutathione, Ubiquinone, Zinc, uremic acid. My biographical research leads me to a conclusion that oxygen played a very serious role in evolution of such a difficult life form as a human bean and other forms of life. In sense of ecological problem, I understood that humanity has to modify technology processes by decreasing the release of oxidizing agents in atmosphere. But by the way it is a serious goal for pharmaceutical researches to search for new substances with a high antyoxydative potential and I consider that this role is the main cause we cannot dodge otherwise the harm of this processes in our metabolism.