Citrus medica L. commonly known as Otroj, is an important medicinal plant reputed for its nutritious and therapeutic uses. The present work was undertaken to investigate the protective effect of the ethanolic extract of otroj (EEOT) against isoproterenol (ISO)-induced cardiotoxicity in rats. In addition, the antioxidant activity and the phenolic and flavonoidal contents were determined. Rats were administered EETO (250 and 500 mg/kg) or vehicle orally for 15 days along with ISO (85 mg/kg, s.c.) on the 14th and 15th day. ISO induced cardiac dysfunction, increased lipid peroxidation and alteration of myocyte-injury specific marker enzymes. ISO also showed an increase in levels of plasma cholesterol, triglycerides (TG), LDL-C, and VLDL-C. Moreover, the histological investigations showed myocardial necrosis and inflammation. EETO treatment brought the above parameters towards normal level. Moreover, in vitro DPPH radical scavenging and β-carotene-linoleic acid tests of the EEOT exhibited a notable antioxidant activity in both assays used. In addition, histopathological examination reconfirmed the protective effects of EEOT. Thus, the present study reveals that C. medica alleviates myocardial damage in ISO-induced cardiac injury and demonstrates cardioprotective potential which could be attributed to its potent antioxidant and free radical scavenging activity.