Polycystic ovarian syndrome (PCOS) is a complex endocrine and metabolic disorder. Chlorogenic acid (CGA) bears antioxidant properties with protective effects on different tissues. This study was conducted to evaluate the effect of CGA on follicular development, hormonal status and biomarkers of oxidative stress in a rat model of PCOS. In this experimental study, 18 rats were divided into three equal groups including: control, non-treated PCOS [(estradiol valerate (EV): 40.00 mg kg intramuscularly)], and PCOS-CGA (EV: 40.00 mg kg intramuscularly and CGA: 100 mg kg intraperitoneally once a week for eight consecutive weeks). At the end of treatment period, all rats were anesthetized. Then 5.00 mL blood samples of rats in the three groups were taken and prepared for hormonal analyses and their ovaries were isolated and dissected mechanically free of fat and mesentery. The ovaries underwent the following analyses: Morphological study with Hematoxylin and Eosin staining and biochemical study using the malondialdehyde (MDA) level and total antioxidant activity. Data were analyzed using one-way ANOVA and post hoc Tukey's test. The serum level of luteinizing hormone, estrogen, testosterone, antioxidant capacity, glutathione and the number of cystic follicles in the PCOS group treated with 100 mg kg Chlorogenic acid compared to the non-treated PCOS group were significantly decreased, however, the serum level of follicle stimulating hormone, progesterone, MDA and the number of secondary, graafian follicles and corpus luteum were significantly increased. Chlorogenic acid could be effective in ameliorating follicular development as well as hormonal and biochemical disorders in rats with PCOS.