Menopause is a chronic endocrine deficiency state. 17β-oestradiol regulates gene expression, mitochondrial function and immune responses. Physiological levels in premenopausal women are essential for optimal reproductive, cardiometabolic, brain, and musculoskeletal health. Consequently, 17β-oestradiol deficiency (menopause) is associated with wide-ranging symptoms and an increased risk of chronic inflammatory diseases including osteoporosis, obesity, diabetes, cardiovascular disease, dementia, and cancer. Failing to understand that 17β-oestradiol regulates numerous physiological processes in multiple tissues and organ systems, not just the reproductive system, results in delayed or missed diagnosis and under-treatment of menopause. Failing to offer women timely and effective treatment for menopausal symptoms causes unnecessary suffering and impacts negatively on women’s health and life spans. Transdermal 17β-oestradiol, with or without body-identical progesterone, effectively and safely treats menopausal symptoms, improves quality of life, reduces chronic disease morbidity, and reduces the risk of premature death. In this chapter we describe the biophysiological effects of 17β-oestradiol throughout the female body, to facilitate an improved understanding of the health risks associated with untreated menopause. We also discuss whether menopause should be considered a natural life event or a disease. All peri- and postmenopausal women, including those with minimal or no menopausal symptoms, should receive accurate, evidence-based, non-biased, personalised information about menopause and menopausal hormone therapy (MHT); and all women who want MHT for distressing menopausal symptoms and/or to mitigate future health risks should have access to it. Use of body-identical MHT supports healthy aging and is likely to translate into better health outcomes for women.