A group of 237 elderly patients with dementia of Alzheimer type (DAT) or multi-infarct dementia (MID) was randomly selected in a large geriatric institution in Milan. Mean age of the sample was 78.9 years, 160 (67.5%) were DAT patients and 77 (32.5%) were MID patients. Half of the sample had low levels of autonomy and after 4 years 183 (77.2%) patients were dead. Predictors of mortality, according to a univariate analysis, were age, level of autonomy and type of diagnosis (DAT vs. MID). Mortality rate after 4 years was significantly higher (p less than 0.001) in DAT (86.9%) than in MID (57.1%) patients.