The worsening, every year, the ecological situation in the world leads to the effect of various toxicants on a person, the formation of free radicals in his body and the development of diseases, including cancer. With their high chemical activity, free radicals form oxidative stress, which leads to intoxication, damage and cell death. One of the main tools in removing toxins from the body is not only enzymes of the cytochrome P450 family, but also the human antioxidant system. Various gene polymorphisms responsible for protecting the body from toxins can lead not only to a decrease in the production of enzymes that carry out the oxidative biotransformation of toxins, but also to a decrease in the protective function of antioxidant system. For 30 patients suffering from chronic and dangerous diseases, molecular genetic studies were carried out and gene polymorphisms responsible for antioxidant system. The genetic characteristics of the antioxidant status described in the article, a prophylactic doctor should recommend a detoxification program, individual nutrition, taking into account the necessary nutritional supplements.