Objectives: This study aimed to assess the protective impact of Cornus mas extract and treadmill exercise on hormonal and metabolic parameters in adult rats with polycystic ovary syndrome (PCOS). Materials and Methods: Forty female Wistar rats were divided into control and experimental groups. The experimental group was further divided into 5 subgroups, namely PCOS control group (G1), PCOS group treated with C. mas extract (100 mg/kg/orally/ daily) (G2), PCOS group treated with scheduled treadmill exercise (G3), PCOS group treated with both extract and exercise (G4), and PCOS group treated with C. mas extract and treadmill exercise (G5). PCOS was induced in G1 by a single injection of estradiol valerate (16 mg/kg, IM). After a 3-week treatment period, all rats were anesthetized and their blood samples were collected for testing the levels of glucose, insulin, aromatase, and hormones (LH, FSH, testosterone, and estrogen). Then their ovaries were removed for histopathological examination. Results: Serum levels of FBS, insulin, luteinizing hormone [LH], follicle-stimulating hormone [FSH], and testosterone were significantly increased in PCOS compared to the control group (P < 0.05); however, these levels were significantly decreased in the treated groups compared to PCOS (P < 0.05). Serum estrogen levels and aromatase activity were significantly decreased in PCOS compared to the control (P < 0.05); however, they were significantly increased in the treated groups compared to PCOS (P<0.05). PCOS led to a reduction in the number of follicles, which was prevented by C. mas extract. Conclusions: In sum, C. mas extract and treadmill exercise had a positive impact on LH, FSH, testosterone, estradiol, aromatase, FBS, and insulin levels compared to the PCOS group.