An association between late-onset Alzheimer's disease, vascular dementia and the common polymorphic alleles of the gene coding for apolipoprotein E, epsilon 2, epsilon 3, and epsilon 4, was assessed in a population sample of 393 elderly Finnish men aged 70 to 89 years. Of them, 7% suffered Alzheimer's disease and 3% had vascular dementia. Among those who suffered Alzheimer's disease, there was a statistically significant excess of the epsilon 4 allele. No such an association was observed between the apolipoprotein E alleles and vascular dementia. We conclude that the apolipoprotein E polymorphism confers information about a risk of Alzheimer's disease in this population sample of elderly Finnish men.