Background and Purpose Ventricular enlargement and white matter lesions are frequent findings on cerebral magnetic resonance imaging scans of elderly subjects. In demented subjects they seem related to the severity of the dementia, but in nondemented subjects their clinical significance is less clear. We investigated the relation of size of the lateral ventricles and white matter lesions with cognitive function in a population-based random sample of nondemented elderly persons.Methods The study population consisted of 90 subjects, aged 65 to 84 years, who were randomly selected from the cohort of the Rotterdam Study, and who were not demented. The presence of white matter lesions and the ventricle-tobrain ratio were assessed on magnetic resonance scans. Participants were tested with a neuropsychological battery that covered a broad range of cognitive functions.Results Ventricular enlargement and white matter lesions were both and independently associated with poorer performance on all tests. After adjustment for age and sex, ventric-