Abstract： The purpose of this study is to evaluate the effect of oligomeric grape seed proanthocyanidins (GSP) on isoproterenol (ISO)-induced cardiac remodeling in rats. ISO was given subcutaneously (5 mg-kg-1, sc,7 days) to induce cardiac remodeling in rats. Therapeutic groups were given GSP (50, 100, and 150 mg-kg-1)after ISO treatment. After 2 weeks intervention, heart rate (HR), left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), rate of rise of left ventricular pressure (±dp/dtmax) were examined.The myocardial hypertrophy index was expressed as heart weight/body weight (HW/BW) and left ventricle weight/body weight (LVW/BW), the histological changes were investigated by HE and Van Gieson stain. SOD activity and MDA content in serum, contents of hydroxyproline (Hyp) in the left ventricular tissue were assayed by xanthinoxidase method, thiobarbituric acid (TBA) method and alkaline hydrolysis method, respectively.After the onset of ISO-treatment, GSP therapy potently improved cardiac function, inhibited myocardial hypertrophy, improved cardiac pathology change, decreased the myocardial cross-section area (CSA), collagen volume fraction (CVF) and perivascular circumferential collagen area (PVCA), reduced the content of Hyp in the left ventricular tissue, inhibited the decrease of SOD activity and increase of MDA content in serum. GSP possess protective effect against ISO induced cardiac remodeling in rats, this may be related to reducing the oxidative stress and improving antioxidant capacity.