Though among U.S. women endometrial cancer is the most common invasive gynecological cancer, it has a relatively favorable prognosis. From 1986From -1990, approximately 19% , approximately 19% of U.S. Surveillance, Epidemiology and End Results (SEER) Program cases were diagnosed in women less than 55 years of age; however, the age-specific incidence (per 100,000) peaked at 70-74 years (110.7), which was 2.85 times the rate reported at 50-54 years (38.9). The incidence under 50 years was 2.19 times higher in U.S. White compared with US. Black women; for uterine corpus cancers diagnosed at 50 years and older, the ratio declined but continued to be elevated in Whites (1.46). In contrast, average annual age-adjusted mortality (per 100,000) from 1986-1990 for uterine corpus cancer (1970 U.S. standard) was almost twice as high in U.S. Black women (6.0) as in U.S. White women (3.3). The determinants of age-specific elevated risks in mortality, in contrast to the lesser age-specific risks in incidence experienced by U.S. Black women compared with U.S. White women, may be explored with respect to socioeconomic and cultural factors that influence the distribution of epidemiologic risk factors such as reproductive history, choice of contraception methods, hormone replacement therapy, obesity, and dietary factors; age-specific prevalence of hysterectomy for other gynecological conditions; quality of medical care and surveillance practices; genetic factors influencing susceptibility; and tumor-associated biological factors. The majority of risk factors and medical conditions associated with endometrial cancer are related directly or indirectly to the levels and metabolic effects of the reproductive hormones, namely estrogens and progestogens. The molecular, genetic, and epidemiologic characterization of endometrial cancer is attempting to delineate the multiple steps in the natural history of estrogen-induced or estrogen-responsive neoplasms.