Some Mammalian aging processes involve effects of steroids on the brain and pituitary. An ovary-dependent, neuroendocrine aging syndrome of laboratory rats and mice is described in this article. This syndrome can be attenuated during aging by chronic ovariectomy and can be prematurely induced in young rodents by sustained exposure to estradiol (E2). The limited follicular stock in the ovary is proposed to be a major pacemaker of aging in this neuroendocrine syndrome; ovarian aging may interact with neuroendocrine aging. Ovary-independent neuroendocrine changes occur as well. We also discuss developmental influences on adult aging in rodents and other examples in which adult lower mammals are sensitive to long lasting effects of steroids on the brain and pituitary. Possible molecular mechanisms are considered. In view of the long lasting effects of E2 and other steroids on lower mammals, the potential for long term effects of ovarian steroids on the human brain and pituitary warrants continued evaluation.