By analyzing the level of pro-oxidant molecules in blood and tissues, such as malondialdehyde, nitric oxide, xanthine oxidase, hydrogen peroxide, superoxide anion radical, as well as the activity of antioxidant enzymes such as superoxide dismutase (superoxide dismutase—SOD) and catalase (catalase—CAT), glutathione reductase, and glutathione peroxidase, we come to the conclusion that the level of oxidative stress in PCOS patients increases [8]. The gene discussed is CAT; the disease is polycystic ovary syndrome.