Breast cancer is a major health problem in America, accounting for almost one-third of cancer-related deaths in women. The prevention of breast cancer through dietary modification is an active area of clinical and epidemiologic research. It has been proposed that the dietary supplementation of vitamin E, a lipid-soluble antioxidant, may reduce a woman's risk of developing breast cancer. In animal models, vitamin E has decreased the incidence of carcinogen-induced mammary tumors. Intake and serum levels of vitamin E and their relation to breast cancer have been evaluated in epidemiologic studies. Results of epidemiologic studies, however, have been conflicting. In this review, we examine the evidence that is available pertaining to the relationship between vitamin E and breast cancer. Although epidemiologic study results have been inconsistent, further study of this nontoxic vitamin is warranted. Particular attention should be paid to the interactions of other antioxidants with vitamin E and to the duration and timing (pre- vs. postmenopausal) of vitamin E use in determining its preventive utility in breast cancer.