We reanalyzed and compared current prevalence estimates of Alzheimer's disease in Europe. Studies characterized as follows qualified for comparison: dementia defined by the Diagnostic and Statistical Manual for Mental Disorders, 3rd edition, or equivalent criteria; Alzheimer's disease diagnosed by the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association or equivalent criteria; case-finding through direct individual examination; appropriate sample size; and inclusion of institutionalized persons. Of the 23 European surveys of dementia considered, six fulfilled the inclusion criteria. When age and sex were considered, there were no major geographic differences in the prevalence of Alzheimer's disease across Europe. Overall European prevalence (per 100 population) for the age groups 30 to 59, 60 to 69, 70 to 79, and 80 to 89 years was, respectively, 0.02, 0.3, 3.2, and 10.8. Prevalence increased exponentially with advancing age and, in some populations, was consistently higher in women. Prevalence remained stable over 15 years in one study.