Objectives. The objective of this study was to evaluate the effect of vitamin E on the oxidative stress parameters and antioxidant defense enzymes in the heart and aorta of 6-n-propylthiouracil (PTU)-induced hypothyroid rats. Methods. The animals were divided into 4 experimental groups: Group 1 (Euthyroid) received tap water, Group 2 (Hypothyroid) received 0.05 % of PTU in dissolved in their drinking water, Group 3 (PTU+Vit E) hypothyroid rats treated with vitamin E, and Group 4 (Euthyroid+Vit E). Vitamin E was injected daily (20 mg/kg) to groups 3 and 4 via daily gavage for 6 weeks. Malondialdehyde (MDA) levels, total thiol levels, and the activities of Cu, Zn-superoxide dismutase (SOD) and catalase (CAT) were evaluated in the aortic and cardiac tissues. Results. A significant decrease of thyroxine (T4) serum levels confirmed hypothyroidism in rats, which received PTU. The MDA level increased and total thiol level decreased in the hypothyroid group compared to control group (p<0.001). Th e activities of SOD and CAT significantly decreased in the hypothyroid rats in comparison to the control. Vitamin E treatment resulted in increased levels of total thiol, SOD, and CAT within aortic and cardiac tissues and decreased levels of MDA in comparison with the hypothyroid group (p<0.01−p<0.001). Conclusions. PTU-induced hypothyroidism resulted in oxidative stress. Chronic administration of vitamin E to hypothyroid rats decreased the oxidative stress markers in the aortic and cardiac tissues.