Despite a growing list of potential new risk factors for Alzheimer's disease (AD), one of the oldest remains controversial. Is female gender a risk factor for AD? It is likely that the greatest influence on the gender differential in crude prevalence rates is the increasing incidence of dementia with age (Paykel et al., 1994) combined with the greater longevity women (Moritz & Ostfeld, 1990). This must be distinguished from the hypothesis that there may also be a gender difference in the age-specific prevalence rates some dementias such as AD. In turn, this could be due to either a higher incidence dementia in women, or to longer survival times in women following diagnosis. What is the evidence for these hypotheses?