ObjectiveThe aim of this study was to compare serum fetuin-A levels and oxidative stress markers, as indicators of insulin resistance, in women with polycystic ovary syndrome (PCOS) and in healthy controls.MethodsThis prospective case-control study included 46 patients with PCOS and 48 age- and body mass index–matched control women. Levels of serum hormones, fetuin-A, and oxidative stress markers were measured in blood samples taken during the early follicular period from each participant.ResultsFollicle-stimulating hormone (FSH), luteinising hormone (LH), total testosterone levels, and the LH/FSH ratio were found to be significantly higher in women with PCOS than in controls. Serum total antioxidant status, total oxidant status, and oxidative stress index parameters all indicated significantly higher levels of oxidative stress in PCOS patients than in controls. Serum fetuin-A levels, which were analyzed as an indicator of insulin resistance, were higher in the PCOS group than in the control group (210.26±65.06 µg/mL and 182.68±51.20 µg/mL, respectively; p=0.024).ConclusionThe data obtained from the present study suggest that higher levels of both serum fetuin-A and oxidative stress markers might be related with PCOS.