The hypothesis that vascular factors may contribute to the development of Alzheimer's disease (AD) is supported by epidemiologic and pathologic observations. Arterial hypertension and diabetes have been found to be associated not only with vascular dementia, but also with AD; in addition, the treatment of hypertension with calcium antagonists seems to prevent degenerative dementias. Hypertension and hyperinsulinemia favor the deposition of amyloid substance in the brain. The histopathology of AD is marked not only by neurofibrillary tangles and senile plaques, but also by macro and micro congophilic angiopathy and ischemic white matter rarefaction. The specific AD pathological lesions, if isolated, are not able to lead to an evident clinical picture of dementia, which, on the contrary, becomes evident when vascular, mainly subcortical, lesions are associated. These and other observations suggest that vascular factors may have a role in the development of AD. An aggressive approach to these factors could be of value in the prevention of AD.