In our study, estimation of the preventive role of vitamin E against DMBA induced mammary cancer in rats was achieved. Forty albino rats were divided into four equal groups. The first group was normal group; second group was administered Vit E (100mg/Kg B.W/d) by gastric tube; cancer was induced in third group by DMBA (50 mg/kg B.W); fourth group administered DMBA + Vit E. Our results revealed that cancer induced by DMBA significantly reduced the body weights and CAT activity of rats, increased MDA levels & altered the histopathological picture. Meanwhile vitamin E ameliorated these alterations. Our study revealed that vitamin E supplementation provided antioxidant properties & antitumor defense with strong preventive activity against DMBA-induced carcinogenesis.