This study was designed to investigate the protective effect of oleanolic acid (OA) against isoproterenol-induced myocardial ischemia in rat myocardium. Wistar strain rats were pretreated with OA (20, 40, and 60 mg/kg, s.c) for 7 days and then intoxicated with isoproterenol (ISO, 85 mg/kg, sc for 2 consecutive days). Heart were excised from the experimental animals and assessed for the activities of marker enzymes [alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and creatine phosphokinase (CPK)], the levels of lipid peroxide products [thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides (HP) and conjugated dienes (CD)], myeloperoxidase (MPO), lipid profiles [total cholesterol (TC), free cholesterol, ester cholesterol, triglycerides (TG), free fatty acids (FFA) and phospholipids (PL)], and membrane-bound ATPase enzymes (total ATPase, Na(+)K(+) ATPase, Ca(2 +) ATPase, and Mg(2 +) ATPase). Troponin T and I were estimated in plasma. Leakage of cardiac markers, elevated lipid peroxidation with increased lipid profiles and decreased activities of membrane-bound ATPase enzymes were confirmed the severe myocardial damage occurring as a consequence of isoproterenol-induced ischemia, and they also showed the significant improvement effected by oleanolic acid pretreatment. These findings provided evidence that oleanolic acid was found to be protecting rat myocardium against ischemic insult and the protective effect could attribute to its anti-oxidative, anti-hyperlipedemic, and anti-arrhythmic properties as well as its membrane-stabilizing action.