Forty-eight patients with a clinical diagnosis of Alzheimer's disease, 30 patients with cerebrovascular dementia, and 48 normal controls were assessed with a battery of neuropsychological tests designed to measure the following cognitive processes: orientation to time and place, memory, visual-perceptual and constructional skills, language, conceptualization, attention, and executive functions (planning, self-regulation and fine motor coordination). The differences detected were in orientation to time and place, in immediate and delayed recall of a short story, and in naming in which the patients with Alzheimer's disease were significantly disadvantaged. Vice versa, in attention processes, self-regulation, planning, and fine motor coordination tasks the patients with cerebrovascular dementia were more severely impaired; these disturbances resemble some of those occurring in frontal lobe syndromes.