(−) Epicatechin rich foods and (−) epicatechin improve cardiovascular function. Consumption of diets rich in flavonoids is associated with reduced risk of cardiovascular diseases. Oxidative stress resulting from increased production of free radicals associated with decreased levels of antioxidants in the myocardium plays a major role in the pathogenesis of myocardial infarction. This study aims to evaluate the preventive effects of (−) epicatechin on oxidative stress in isoproterenol-induced myocardial infarcted rats. Male Wistar rats were pretreated with (−) epicatechin (20 mg/kg body weight) daily for 21 days. After pretreatment, isoproterenol (100 mg/kg body weight) was injected into the rats at an interval of 24 h for two days to induce myocardial infarction. Isoproterenol induced rat's electrocardiogram showed elevated ST segments and significant increase in the activity of serum creatine kinase-MB, level of serum troponin-T and increased intensities of serum lactate dehydrogenase 1 and 2-isoenzymes. The rats also showed significant increased levels of heart lipid peroxidation products and significant decreased activities of heart superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and levels of reduced glutathione. Pretreatment with (−) epicatechin revealed significant protective effects on all the biochemical parameters and electrocardiogram investigated. Histopathology of myocardium confirmed the present findings. The in vitro study on the effects of (−) epicatechin on scavenging free radical 1,1-diphenyl-2-picrylhydrazyl revealed the free radical scavenging potential of (−) epicatechin. Thus, (−) epicatechin exerts protective effects against isoproterenol-induced oxidative stress thereby reducing cardiac tissue damage by its free radical scavenging and antioxidant effects.