It was once thought that menopause is the result of exhaustion of ovarian follicles. However, it is now known that complex interplay of neurohormonal and ovarian signals heralds the onset of menopause and hypothalamus plays an important role. Increasing dysfunction of these neurohormonal and ovarian factors with aging ultimately leads to reproductive senescence. Early in the menopause transition, the initial event is a decline in circulating inhibin-B levels in the early follicular phase. In the late perimenopause, levels of estradiol (E2) and inhibin-A also fall, inhibin-B levels remain low and follicle stimulating hormone (FSH) is markedly elevated. Serum androgen levels appear to fall with age rather than having any clear-cut relationship to the menopausal transition or menopause.