The clinical significance of dilated Virchow-Robin spaces (dVRS) remains unclear and their impact on cognitive performances has only been reported in small sample studies. Our aim was to assess the association between severity of dVRS and risk of incident dementia and cognitive decline in an elderly cohort. The degree of dVRS in both white matter and basal ganglia were ranked using high-resolution 3D MRI in a population-based sample of 1,778 non-demented participants from 65 to 80 years of age, who had a cerebral MRI at baseline. Cognitive function was assessed and dementia was diagnosed during a 4-year follow-up period. Cox proportional hazard models were used to examine the association between dVRS degree on a four-level severity score and incident dementia. The relationship between dVRS degree and change in cognition was examined using linear mixed effect models. During 6,135 person-years of follow-up, 27 individuals developed dementia. The highest degree of dVRS was associated with a strong increase in the risk of incident dementia independently of other standard risk factors of dementia, both for dVRS in white matter (HR=9.8, 95% CI 1.7-55.3) and in basal ganglia (HR =5.8, 95% CI 1.2-28.4). After further adjustment on white matter hyperintensity volume and brain infarcts, this association remained significant for dVRS in white matter. Higher rate of cognitive decline was found to be related to high degree of dVRS in basal ganglia but not in white matter. These results need confirmation but they suggest that assessment of the severity of dVRS may help identify groups of individuals that are at increased risk of dementia.