In the past decade there has been a growing public interest and resurgence in research in the field of hormonal carcinogenesis. This is due to the widespread use of therapeutic hormonal agents worldwide and to the increasing awareness of the causal association of hormones, both endogenous and exogenously administered, and a variety of human cancers. These associations include estrogens in uterine, cervical, vaginal, liver, testicular, prostatic, and possible breast cancers; progesterone and progestational hormones in breast cancer; androgens and anabolic steroids in hepatic and prostatic cancers. Additionally, gonadotrophins playa role in the etiology of ovarian and testicular cancers and thyroid-stimulating hormones in thyroid cancers. Therefore, hormonal carcinogenesis encompasses the study of both natural and synthetic hormonal agents, including growth factors and other peptide and protein factors, which contribute substantially to the etiology of both human and animal neoplasms, benign or malignant. Hormones may be involved in all aspects of neoplastic transformation, including initiation, promotion, and progression, and the inhibition of these processes. There are a number of important issues in women’s health that need to be addressed. More than 40 million U. S. women are menopausal, and these women have a life expectancy of over 30 years after the menopause. When these figures are multiplied worldwide, the numbers become staggering. After the menopause, estrogen replacement therapy (ERT) is the choice of most women in industrialized countries.