A hospital-based case-control study of the epidemiology of endometrial cancer in women aged 45–74 years was carried out in Connecticut from 1977 to 1979. In total, 167 cases and 903 controls were included. Elevated rsks were associated with the following factors: overweight, nulliparity, few pregnancies, use iof estrogen replacement therapy, older age at menopause, and a history of ovarian or endometrial cancer in mother or a sister. Whites were more frequently aflected than blacks, and better-educated women more often than less-educated women. Use of oral contraceptives was associated with a decreased risk, although the decrease did not reach statistical significance.