Introduction: Polycystic ovary syndrome is one of the most common causes of infertility. 6 to 8 percent of women of childbearing age have this endocrine disorder. Biochemical abnormalities in these patients lead to imbalance of female hormones and increased androgens, which can have consequences such as menstrual cycle disorder, hirsutism, acne vulgaris and androgenic alopecia. Despite the long history of studies on polycystic ovary syndrome, the cause is still unknown. Oxidative stress is an imbalance between the production of reactive oxygen species and the amount of antioxidant. When this balance is disturbed, the result is an increase in the level of oxidative stress. Oxidative stress is currently recognized as one of the major pathophysiologies of many disorders and diseases, including polycystic ovary syndrome. Understanding the mechanisms of oxidative stress is crucial for developing strategies for the prevention and treatment of this disease. In this article, we reviewed the data on the mechanism of oxidative stress in polycystic ovary syndrome.