Estrogen replacement therapy appears to have significant beneficial effects on cognition and mood in the elderly. In recent studies, its use has been associated with short term symptomatic cognitive improvement and with a decreased risk of (or a delay in) developing Alzheimer's disease (AD). Clinical reports are supported by substantial basic scientific evidence of the neuroprotective effects of estrogens. Their specific effects on dementia and cognitive impairment remain to be delineated. Ongoing randomised trials in AD will only provide information on the symptomatic effects of estrogen. Although basic research will progress, there is currently sufficient knowledge to promote active clinical research on the possible disease-modifying or neuroprotective effects of estrogens in the elderly.