The association between the APOE gene and Alzheimer's disease and other forms of dementia has been widely documented, but its relevance as a genetic risk factor in specific ethnic groups other than Caucasians in the United States and Europe is limited. The aim of this work was to describe the distribution of the APOE genotype in 80 subjects of Spanish origin, over 60 years old, who were institutionalized in the Spanish Hospital of Mexico City. Thirty-eight subjects who met the DSM-IV and ICD-10 criteria for Alzheimer's disease or vascular dementia and 42 controls without dementia underwent genotyping. APOE epsilon allele frequencies were as follows: for affected individuals, epsilon2, 7.9%, epsilon3, 69.7%, and epsilon4, 22.4%; for controls, epsilon2, 4.8%, epsilon3, 91.6%, and epsilon4, 3.6%. The higher frequency of the epsilon4 allele in the affected group (chi2 = 14.5; df = 4, p = .006) confirms an association between this APOE molecular variant and dementia in elderly Spaniards.