The interleukin-1 (IL-1) pro-inflammatory cytokine family participates in inflammatory processes and vessel damage involved in neurodegeneration. Recent studies suggest that Alzheimer's disease (AD) and vascular dementia (VaD) may share genetic risk factors. In this study, the frequency of polymorphisms in the genes coding for interleukin (IL)-1alpha, IL-1beta and the IL-1 receptor antagonist (RN) and their genotype associations with late-onset AD and VaD were determined in a Japanese-American cohort of men (n=931) participating in the Honolulu-Asia Aging Study (HAAS). A significant association was found between the IL-1beta (-511) and IL-1RN (+2018) polymorphisms and AD, suggesting that these variants confer an increased risk. Possessing the IL-1beta (-511) T/T genotype was also associated with VaD. There was no difference in the IL-1beta (+3953) frequency among the groups. Our results support the hypothesis that certain genetic variations contained within the IL-1 gene family contribute to the pathogenesis of dementia.