In our study; estimation of the preventive role of vitamin E against DMBA induced mammary cancer in rats was achieved. Forty female albino rats were divided into four equal groups. The first group was normal group received corn oil only; second group was administered Vit E (100mg/Kg B.W/d) dissolved in 4 mL corn oil by gastric tube; cancer was induced in third group by DMBA (50 mg/kg BW); fourth group administered DMBA + Vit E. Our results revealed that cancer induced by DMBA significantly reduced the body weights of rats & altered the histopathological picture of mammary tissues. Meanwhile vitamin E ameliorated these alterations as it inhibited the reduction of rats ՚ body weight and improved the cellular architecture of breast tissues by reducing inflammation, neoplastic tissues and cellular proliferations. Our study revealed that vitamin E supplementation provided antioxidant properties & antitumor defense with strong preventive activity against DMBA-induced carcinogenesis.