Since hormone replacement therapy was introduced 70 years ago, a steady flow of studies has produced evidence of both harmful and beneficial effects. Recent British studies have shown that 60% of women aged 51–7 years have taken hormone replacement therapy,1 with 45% having tried it by the time they are 50.2 In the United States, about 38% of postmenopausal women take hormone replacement therapy. In 2000, 46 million prescriptions were written for Premarin (conjugated equine oestrogens), making it the second most frequently prescribed drug in the United States.3

Women are increasingly encouraged to participate in making decisions about hormone replacement therapy. However, the complexity and uncertainty of information about the treatment can make it difficult for women to make a decision, increasing their reliance on medical advice.4 The publication of the heart and oestrogen-progestin replacement study (HERS)5 and women's health initiative (WHI)6 study, both of which found adverse effects, has added to the confusion. In this article, we define who should be offered hormone replacement therapy and why, describe the reasons why women may wish to take hormone replacement therapy, and clarify the advantages and disadvantages of treatment.