Whether and which genetic factors affect human longevity is unclear. This study assesses the association between the epsilon2 allele of apolipoprotein E (APOE), a putative longevity gene, and extremely old age. This study is based on all centenarians living in Finland in 1991. Subjects were 179 persons (28 men and 151 women) aged 100 years and older (response rate, 97%). The percentages of epsilon2-allele carriers in persons aged 100 to 101, 102 to 103, and 104 years and older were 9% (10/117), 21% (9/42), and 25% (5/20; gender-adjusted p for trend = .01), respectively. The effect was particularly strong in women: 8% (8/100), 18% (6/33), and 28% (5/18; p for trend = .01) by age group, respectively. Low cell numbers prevented clear conclusions being drawn for men. Seventeen percent (30/179) of the adult Finnish population were carriers of the epsilon4 allele, a figure lower than expected, and stable by age group. Carriers of the epsilon2 allele of APOE might be predisposed to reach extremely old age.