Widely conflicting data exist regarding the relationship of dementia to mortality and the relative risk of senile dementia of the Alzheimer type vs multi-infarct dementia with respect to mortality. In a historic prospective study, 202 patients with dementia were matched by age and sex with 202 nondemented controls attending the same geriatric assessment clinic and receiving comparable medical and psychiatric care. The three-year survival rate was 70% for patients with dementia and 84% for controls. Patients with multi-infarct dementia survived more poorly than patients with senile dementia of the Alzheimer type, but the difference did not reach statistical significance. The relative risk associated with dementia in the context of a multivariate analysis was 1.92 (95% confidence [1.25, 2.97]). We conclude that dementia carries a significantly increased risk of mortality but that the survival of patients with dementia may be better than previous reports would suggest.