The menopause marks the permanent cessation of menstruation and heralds the transition in a woman’s life from a reproductive state to a non-reproductive one. Whilst the average age of this landmark varies slightly across the world, the menopause generally occurs in the early fifties and is only truly affected by factors such as smoking and medical and surgical induction of the menopausal state. However, clinical symptoms may precede this, and the physiological changes which occur with the menopausal transition may begin several years prior to the onset of any manifestations. The basis of the clinical and biochemical changes associated with the perimenopausal period is the depletion of ovarian follicles to a critical level.