OBJECTIVE To report on the relationship between serum folate levels and the prevalence of stroke, peripheral vascular disease, cognitive problems and short-term mortality in elderly people. SETTING AND PARTICIPANTS 1171 subjects whose serum folate was determined as part of their clinical examination in the Canadian Study of Health and Aging, a population study of individuals 65 years and older. METHODS Cross-sectional analysis compared relationships between serum folate levels and clinical features; longitudinal analysis examined mortality at follow-up by folate status at the time of the clinical examination. RESULTS Membership in the lowest quartile for serum folate was associated with an increased likelihood of stroke. Those with low folate levels were more likely to be demented, institutionalized and depressed. In the cognitively impaired but not demented group, those with low folate levels scored lower on the Modified Mini Mental State and had more short-term memory problems. CONCLUSIONS Low folate level was a significant explanatory variable for stroke. Low folate levels were common in all types of dementia and were associated with a history of weight loss, lower body mass index and lower serum albumin concentrations. This may reflect the reduced ability of cognitively impaired individuals to eat adequately.