Background. Hormone disorders, stress-oxidative and inflammation in ovarian tissue cause no-ovulation in women with polycyclic ovarian syndrome (PCOS). Several studies have shown the role of exercises in control of sex hormones. Objectives. The aim of this study was to investigate the effect of 6 weeks of swimming training (ST) on serum levels of sex hormones, antioxidant enzymes and oxidative damage of DNA ovarian tissue in rats with PCOS. Methods. In this experimental study, 30 female Wistar rats were divided into 3 groups included control, PCO (letrozole consumption for 28 days intra-peritoneally) and PCO+ST groups. PCOS was induced with 28 days of peritoneal injection of 1 mg/kg letrozole. The ST program was included 6 weeks of ST for 20 minutes per day. At the end of the treatment period, serum levels of LH, FSH, testosterone, estradiol and progesterone, SOD, CAT, GPX, MDA and HOdG-8 in ovarian tissue were measured by ELISA method. Results. ST significantly decreased serum levels of LH, estradiol, testosterone, MDA and HOdG-8 levels (p<0.05) as well as increased SOD, CAT, and GPX enzymes of rats with PCOS (p<0.05). Conclusion. It appears that ST has antioxidant and sex hormone enhancing effects in ovarian tissue of rats with PCOS model.