Endometrial cancer is the commonest gynaecological cancer mostly affecting women in the post-menopausal age group. Rates vary worldwide and are highest in white women in Western populations. Some risk factors are related to reproduction, such as early age at menarche, late age at menopause and nulliparity, while others are more directly oestrogen-related, for example, conditions such as the polycystic ovarian syndrome. Use of unopposed oestrogen replacement therapy is associated with an increased risk, and use of the combined oral contraceptive pill is associated with a decreased risk. The relationship between tamoxifen and endometrial cancer is not established. Obesity, diabetes and hypertension increase the risk of endometrial cancer while smoking, low-fat diets and physical exercise appear to decrease the risk; all of these possibly exert their effects by various indirect influences on oestrogen levels, thus influencing the level of stimulation of the target endometrial epithelium.