This chapter reviews and summarizes evidence on the relationships between nutritional factors as well as breast, endometrial and ovarian cancers. The emphasis in the chapter is on clinical and epidemiologic studies, with the goal of identifying clinically useful strategies for prevention and patient management as well as describing future directions for research. Carcinomas of the breast, endometrium, and ovary are hormone-related cancers that have biologic similarities. Over the past several decades, there has been a considerable amount of research exploring the possible relationships between various nutritional factors and breast cancer. Laboratory animal studies quite consistently demonstrate that except for a specific tumor-promoting effect of linoleic acid, the effects of dietary fat on tumor growth is attributable to the high-energy content of a high-fat diet, rather than the content of fat. Given that a reduction in fat intake has been hypothesized to influence breast cancer risk by reducing serum estrogen concentrations, various feeding studies and small diet intervention trials have examined the effect of dietary fat reduction on serum estrogen levels. Alcohol intake has been consistently and positively associated with risk for breast cancer in epidemiologic studies. © 2004 Elsevier Inc. All rights reserved.