At least 20 million postmenopausal women worldwide now use some form of hormone replacement therapy. This figure is increasing because the resistance of the medical community to these therapies is diminishing and because of increasing acknowledgement of the benefits of such therapies on the cardiovascular system. This is a remarkable development for a medication originally used to relieve menopausal symptoms such as hot flushes and to prevent bone loss. Although several mechanisms are now accepted to be involved in this protection from cardiovascular disease, changes in plasma lipoproteins remain a major area of research interest. The main issue in this field, whether the addition of a progestogen to postmenopausal oestrogen ('combined therapy') will diminish the benefits on the cardiovascular system, remains unresolved, but combined therapies have now been formulated that minimize the potentially detrimental effects of progestogens on plasma lipoproteins. Recent findings of interest include the effects of these therapies on plasma lipoprotein (a) concentration and on LDL particle size. Studies of the mechanisms behind such changes are needed.