Abstract: Background and Objective: Cardiovascular problems are the leading cause of death worldwide. Myocardial infarction (MI) is a severe health problem since it kills more people than any other type of cardiac disease. The current study investigated the preventive effect of Cassia alata (C. alata) leaf methanol extract on isoproterenol (ISO)-induced MI in rats. Materials and Methods: A total of 24 male Wistar rats were divided into 4 groups (n = 6). Group I rats received a standard pellet diet, Group II rats were treated with C. alata leaf extract (100 mg kg–1) for 14 days and Group III rats received a subcutaneous injection of ISO (85 mg kg–1) for the last two consecutive days (13th and 14th day) and Group IV rats received C. alata (100 mg kg–1) for 14 days with ISO for last 2 days. Results: Cardiac serum markers, lipid peroxidative, inflammatory and fibrotic markers were increased and decreased cellular antioxidants in ISO-induced rats. At the same time, the pre-treatment of C. alata leaf extract reduced the activities of cardiac marker enzymes and lipid peroxidative markers and enhanced the antioxidant status in ISO-induced rats. Further, C. alata leaf extract pre-treatment inhibited inflammatory markers and downregulated the fibrosis markers in ISO-induced rats. Conclusion: The findings of the present study reveal that C. alata leaf extract attenuates cardiotoxicity through the modulation of oxidative stress and inflammation in ISO-induced MI rats. The antioxidant, free radical scavenging and anti-inflammatory properties of C. alata leaf extract have been connected to its cardioprotective properties.