ABSTRACT: Introduction & Objective: Flavonoids are polyphenolic compounds, which are considered as antioxidants due to their ability to scavenge free radicals and inhibit enzymes in oxygen-reduction pathways. Various studies have shown that these products reduce the cardiovascular disease mortalities. Heart failure is one the main cause of mortality in diabetic patients. It is believed that diabetes has deleterious cardiomyopathic effects, which would lead to heart failure. Several evidences indicate that oxidative stress is an important factor in the pathogenesis of diabetic complications, including cardiomyopathy. The objective of the present study was to examine the effects of hesperidin on cardiac function parameters in experimental diabetes mellitus type 1 (DM1). Material & Methods: Diabetes mellitus was induced in rats by single intraperitoneal injections of streptozotocin (60mg/kg). Diabetic rats were given oral Hesperidin (500 mg/kg) for two months. Afterwards, the animals' hearts were used to study left ventricular systolic pressure (LVSP), rate of rise (+dP/ dT) and rate of decrease (-dP/ dT) of left ventricular pressure, using Langendorff isolated heart apparatus. Results: Diabetes significantly reduced the LVSP, +dP/ dT and -dP/ dT compared to the control group(p<0.05). Hesperidin significantly improved all measured parameters in diabetic animals(p<0.05). Conclusion: These results show that hesperidin can improve diabetic cardiomyopathy in experimental diabetes mellitus.