Currently there has been an increased interest globally to identify antioxidant compounds that are pharmacologically potent and have low or no side effects for use in preventive medicine. This study was designed to evaluate the protective effect of gallic acid on cardiac marker enzymes, troponin-T, LDH-isoenzyme pattern, lipid peroxidation products and antioxidant status in isoproterenol (ISO)-induced myocardial infarction in male Wistar rats. Male albino Wistar rats were pretreated with gallic acid (15 mg/kg) daily for a period of 10 days. After the treatment period, ISO (100 mg/kg) was subcutaneously injected to rats at an interval of 24 h for 2 days. ISO-induced myocardial damage was indicated by increased activities of marker enzymes such as creatine kinase, creatine kinase-MB, aspartate transaminase, alanine transaminase and lactate dehydrogenase in serum and the levels of troponin-T in the serum. Increased LDH-isoenzyme bands (LDH-1 and LDH-2) were also observed in serum of ISO-induced rats. In addition to these diagnostic markers, the levels of lipid peroxidation products in plasma and the heart were significantly (P<0.05) increased and the activities of enzymic antioxidants such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase in the heart and non-enzymic antioxidants such as glutathione, vitamin C and E in plasma and the heart were significantly (P<0.05) decreased in ISO-induced rats. The level of uric acid in plasma was significantly (P<0.05) increased in ISO-treated rats. Gallic acid pretreatment showed significant protective effect on all the biochemical parameters studied. Histopathological findings of gallic acid pretreated myocardial infarcted heart confirmed the biochemical findings of this study. Thus, gallic acid protects the myocardium against isoproterenol-induced oxidative stress.