Background/Aims: Our objective was to compare the mortality risks of patients with early- and late-onset dementia with non-demented controls of the same age range and to analyse the mortality risks in subtypes of dementia. Methods: We included 1,203 subjects from our memory clinic. Patients with dementia were subdivided into 2 groups, with early- (<65 years) or late-onset dementia (≥65 years), and compared with non-demented controls of the same age range. We used Cox proportional hazard models to estimate mortality risks. Results: When compared to non-demented controls of the same age range, the patients with early-onset dementia had a strongly elevated mortality risk [hazard ratio (95% confidence interval) = 43.3 (3.1-600.4)], while those with late-onset dementia had a moderately increased mortality risk compared to older controls [hazard ratio (95% confidence interval) = 3.4 (1.8-6.2)]. An additional analysis showed that, adjusted for age, Alzheimer's disease seemed to have the most benign course, with a fourfold increased mortality risk. Dementia with Lewy bodies and vascular dementia (frequently seen at older age) and frontotemporal lobar degeneration and 'other dementias' (often found at younger age) had a six- to eightfold increased mortality risk. Conclusion: Dementia is a risk factor for death. Especially in young patients the impact of dementia on mortality is high. Copyright © 2008 S. Karger AG.