Objectives: The risk for cardiovascular disease is significantly high in diabetes mellitus. Experimental evidence suggests that oxidative stress plays a dominant role in the pathogenesis of diabetes mellitus. Caffeic acid phenethyl ester (CAPE), an active component of propolis, has several biological and pharmacological properties, including antioxidant, anti-inflammatory, anti-carcinogenic, antiviral, and immunomodulatory activities. In light of the antioxidant ability of CAPE, the effects of CAPE on the antioxidative status of cardiac tissue were investigated in streptozotocin (STZ)-induced diabetic rats.