Epidemiological data have shown that Western women have a higher incidence of breast cancer and coronary heart disease (CHD) than Asian women, and have implicated hormonal factors associated with differences in incidence of breast cancer. Whether hormones play a detrimental or beneficial role in CHD is inconclusive. Comparison of the serum lipid and hormone level in Bantu and Japanese women (low risk populations) compared with Caucasian women (high risk population) showed higher oestrogen levels in young Bantu and Japanese women, but comparable levels in postmenopausal women from each ethnic group. Comparison of subgroups of Caucasian women at different risk for breast cancer showed marked difference in the hormone profile, while the serum lipid levels were similar except in women with late pregnancy. Although many studies may have failed to consider subgroups of women at risk for CHD, data suggests that premature castration causes little change in total oestrogens or serum lipids and would suggest that oestrogens, at least during this time of life, play little part in coronary heart disease.