Cardiovascular diseases are the leading cause of death globally and the increase in cardiovascular mortality and heart failure are common in all age groups. This may be due to accelerated atherosclerosis and compelling epidemiological and clinical data indicate that diabetes mellitus increases the risk of cardiac dysfunction and heart failure. The present study was conceived to explore the cardioprotective activity of cucurbitacin enriched fraction of Momordica dioica Roxb (MDR) fruit (CEFMD) against isoproterenol (ISO) and stress-induced cardiotoxicity on normal rats. CEFMD was prepared and standardized by precipitation test and TLC fingerprint. The fraction was evaluated for in vitro antioxidant and free radical scavenging activities like DPPH and reducing power. The in vivo cardioprotective activity of CEFMD was done at three doses (100, 200 and 400 mg/kg) for 15 days and activity was compared with that of carvedilol. The various parameters like non-serum parameters-ECG, heart rate, wet heart weight, serum biomarkers (CKMB, LDH, SGOT), endogenous antioxidant enzymes like SOD, CAT, GSH and MDA were determined in heart tissue homogenate. To support the activity histopathological observations were also done. The results of our study reveal the cardioprotective activity of CEFMD and significant activity was observed at low dose and activity was decreased as the dose increases. The same was observed in all parameters and further research is required to find out the exact reason for it.