Menopause is diagnosed after 12 months of amenorrhoea resulting from the permanent cessation of ovarian function. The mean age at menopause is 51 years. The perimenopause, a time of changing ovarian function, precedes the final menses by several years. The physiology and clinical manifestations of this transition to menopause are not well understood; however, some symptoms, such as hot flashes, certainly begin in the perimenopause. Causal associations between menopause and several symptoms and diseases are proposed. The evidence for these associations varies and is reviewed. Hormone replacement therapy can be directed at symptom relief or at prevention or treatment of chronic diseases. Doses and routes of hormone replacement therapy vary by indication. Complications of hormone replacement therapy depend on the regimen used. Knowing the expected vaginal bleeding pattern for each hormone replacement therapy regimen is important, since unexpected bleeding may signal endometrial hyperplasia. Postmenopausal hormone therapy is a complex intervention that produces positive and negative specific health effects. Overall, based on observational studies, postmenopausal women who use hormones have a 30-50% lower all-cause mortality rate than those who do not use hormones. It is important to recognise that the value that individual women place on various health outcomes associated with hormone replacement therapy may differ. Thus, the decision to use hormone replacement therapy should be made jointly by each woman and her health-care provider, after careful consideration of possible benefits, risks, and her personal preferences.