This study aimed to examine the possible association between the oxidative stress parameters and clomiphene citrate resistance in polycystic ovary syndrome. The demographic data, hormone profiles and oxidant and antioxidant values of 50 clomiphene citrate-resistant polycystic ovary syndrome patients (Group 1), 32 clomiphene citrate-sensitive polycystic ovary syndrome patients (Group 2) and 87 non-polycystic ovary syndrome patients (Group 3) were compared. The average age, follicle-stimulating hormone, oestradiol, thyroid-stimulating hormone and prolactin values of the three groups were found to be homogeneous. Ferroxidase, catalase and myeloperoxidase levels were determined to be lower in the clomiphene citrate-resistant group compared to clomiphene citrate-sensitive and non-polycystic ovary syndrome groups (p