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Abstract Background & aim: Polycystic Ovary Syndrome (PCOS) is one of the most common endocrine disorders which affect 5-7 % of women in their reproductive age. Heracleum persicum (Golpar) contains compounds with anti-inflammatory, antioxidant, and antimitosis properties. The purpose of this study was to evaluate the therapeutic effect of ethanol extracts of Heracleum persicum fruit on polycystic ovary syndrome in rats. Methods: In the present experimental study, thirty rats (200±20gr), were injected with 2 ml of estradiol valerate subcutaneously and six other rats were considered as the control group (intact). Sixty days after injection, the rats were divided into control, sham and experimental groups. The experimental group was treated with 200, 400 and 800 mg/kg BW of of Golpar extract interaperitoneally for ten days. The serum levels of LH, FSH, estradiol and testosterone were measured by ELISA and each serum were analyzed using ANOVA. Results: A significant decrease was seen in serum levels of LH (P< 0.05), estradiol (p< 0.01) and testosterone (p< 0.01) in three experimental groups compared with the control group. Whereas, a significant increase in the mean FSH (p< 0.05) concentrations was observed in the groups receiving high dose. Conclusions: Due to the decreasing effect of Heracleum persicum (Golpar) extract on LH, estradiol and testosterone levels and increasing in FSH level in PCOS rat, it seemed that the Golpar had a therapeutic effect on patients with this disease.