Presenilin-1 is known to contribute to the pathogenesis of Alzheimer's disease. The association of an intronic polymorphism (rs165932) of the presenilin-1 gene with late-onset Alzheimer's disease has been documented. However, contradicting results have been shown in different populations. The aim of the current study is to determine whether there is an association between the intronic polymorphism of the presenilin-1 gene and late-onset Alzheimer's disease in a cohort of Turkish patients. One hundred and seven participants with dementia of the Alzheimer type and 106 age-matched controls were genotyped according to BamH I restriction site in intron 8 of the presenilin-1 gene. The distribution of genotypes and alleles did not significantly differ according to chi(2) test (P = .52, P = .32, respectively), when the control and patients were compared. Consequently, our results showed that the 1/1 genotype does not increase the risk of developing late-onset Alzheimer's disease in the Turkish population.