Myocardial infarction (MI) is an important cause of mortality around the world. Isoproterenol (ISO) is a synthetic catecholamine found to cause toxicity leading to severe stress in the myocardium of experimental animals. The aim of the present article is to investigate cardioprotective activity of astaxanthin against ISO-induced cardiotoxicity in adult rats, in an attempt to understand its mechanism of action, which may pave the way for possible therapeutic applications. Oral administration of astaxanthin at a concentration of 50 and 100 mg/kg b.wt. daily for 58 days showed a significant protection against-induced alteration in plasma and cardiac SOD, GPx, GSH and CAT as well as CK-MB, LDH, ALT and AST activities. In addition, astaxanthin reduced plasma CK-MB, LDH, ALT and AST as well as cardiac MDA and HP levels as compare to control group. In conclusion, astaxanthin renders resiliency against isoproterenol cardiotoxicity due to its antioxidant and free radical scavenging activity that might serve as novel adjuvant therapy with isoproterenol.