The citrus aurantium has traditionally been used by the people of Iran. The aim of this study was to evaluate the protective effects of hydroalcholic citrus aurantium extract on electrocardiographic, biochemical and pathological changes after myocardial infarction induced by isoproterenol in rats. 24 male Wistar rats were divided randomly into 4 groups: Control, extract, isoproterenol, and isoproterenol + pre-treatment with extract for two weeks. At the end of the experiment, ECG was recorded in lead II. Finally, blood samples were taken and cardiac marker enzymes such as creatine kinase, lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase, along with oxidative stress markers such as malondialdehyde, superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase, and lipid profile were determined.Myocardial infarction induced by isoproterenol produced a significant increase in the heart rate, ST-segment elevation, decrease in R amplitude, and a significant increase in the level of cardiac marker enzymes: LDH, CK-MB, AST, ALT and ALP in serum. Also, isoproterenol significantly reduced SOD, CAT, GSH, GP X and increased MDA activity, disturbance in lipid profile, and inflammatory process in cardiac myocytes. Pretreatment with citrus aurantium extract for two weeks significantly reduced the effect of isoproterenol on electrocardiographic parameters, cardiac biomarkers, oxidative stress indices, lipid profile and cardiac myocytes injuries.Results indicated that citrus aurantium extract ameliorates the cardio-toxic effects of isoproterenol through reinforcement of antioxidant defense system and may be of value in treatment of myocardial infarction. Further studies are required to determine the precise mechanism of the therapeutic effect of the extract.