Introduction: Polycystic ovary syndrome (PCOS) is one of the most common endocrinological pathologies in women during their reproductive years with ovulatory dysfunction, abdominal obesity, hyperandrogenism and insulin resistance. The aim of the present research was to evaluate the total antioxidant capacity (TAC), total oxidant status (TOS), free testosterone, ovarian morphology and estrous cyclicity in the estradiol valerate (EV)-induced PCOS rat model and the effect of treadmill and running wheel exercises on these parameters. Methods: Fifty female Wistar rats were randomly selected (220 ± 20 g). They had every 2 to 3 consecutive estrous cycles during 12 to 14 days. The first two groups were divided into control (n=10) and polycystic (n=40) that were induced PCOS by EV injection after 60 days. The polycystic groups were divided into three groups (n=10 in each group) PCOS, experiment group with treadmill exercise (running for 28 m/min at 60 min/day) and experiment group with running wheel exercise (running daily for 4 hours) for 8 weeks. Results: The PCOS rats had significantly higher testosterone, TOS and lower TAC than control. Eight weeks of treadmill and running wheel exercise significantly increased serum levels of TAC (just for treadmill exercise) and decreased level of TOS and T (just for treadmill exercise) in EV-induced PCOS rats compared to PCOS group. Ovarian morphology and estrous cycle was almost normalized in the PCOS exercise (treadmill and running wheel) groups. Conclusion: The present study demonstrate EV-induced PCOS in rats is associated with an increased oxidative stress and this increase can be returned to normal levels by exercise.