Changes in female reproductive function occur relatively early during the life span in many mammalian species. Therefore, this physiological system is an excellent model system in which to study the effects of age on specific endocrine relationships since changes occur prior to the occurrence of multiple pathologies associated with later stages of aging. Data from several laboratories suggest that changes in hypothalamic, pituitary and ovarian function may contribute to age-related deterioration of fertility in females. We will focus our attention on the role of hypothalamic changes in the cascade of events that eventually lead to acyclicity and infertility. Data suggest that changes in the diurnal rhythmicity of catecholaminergic neurotransmitters and their receptors occur during middle age. These changes may regulate the pattern of release of GnRH since alterations in the pulsatile pattern of LH secretion also become detectable at this age. Some age-related changes in hypothalamic and pituitary function are not irreversible or absolutely determined. Instead it appears that the ovarian steroidal milieu modulates the rate of aging of several aspects of hypothalamohypophysial function. In summary, changes in hypothalamic and pituitary function appear to contribute to the aging of the female reproductive system.