Objective Ischemia-mediated oxidative stress and inflammation have been reported to be important contributors to the pathogenesis of polycystic ovary syndrome (PCOS). Ischemia-modified albumin (IMA) is a novel marker generated under ischemic and oxidative conditions and may reflect disease activity in distinct disease states. Therefore, we investigated whether the serum IMA levels are affected in infertile PCOS patients. Methods Forty-six patients with infertile PCOS, 30 patients with unexplained infertility, and 31 age- and body mass index (BMI)-matched controls were included in this cross-sectional study. Biochemical parameters, serum IMA levels, and their correlations with serum testosterone and insulin resistance were determined for each subject. Results In patients with infertile PCOS, the serum IMA levels were significantly elevated (p=0.003) compared with unexplained infertility patients and controls. A correlation analysis suggested that the IMA levels only correlated with the serum free testosterone levels in PCOS patients (r=0.43, p=0.028). Conclusion Elevations in the serum IMA levels in infertile PCOS patients may suggest a possible additional role of oxidative stress mechanisms in disease pathophysiology. Moreover, correlation between serum IMA and testosterone levels may influence the quality of oocytes via alterations in the balance of critical follicular fluid factors in the follicular microenvironment.