Telomeres generally shorten with age. An accelerated shortening of the telomeres has been linked to several age-related disorders. We hypothesized that the relative length of telomeres could discriminate between patients with late-onset Alzheimer's disease (AD) and vascular dementia (VaD). A quantitative real-time PCR method was used to calculate the relative telomere length in 76 age-matched and sex-matched, newly diagnosed late-onset AD or VaD patients recruited from our Memory Unit. No significant difference was found in the relative telomere length between AD and VaD cases neither in men (P=0.315) nor women (P=0.12). Thus, we could not confirm that the length of telomeres would predict which form of dementia, late-onset AD or VaD that develops.