This article summarizes the role of imaging in the evaluation of cognitive disorders of the elderly. The primary goal of imaging is to exclude potentially reversible dementia due to intracranial lesions such as tumor, subdural hematoma or normal pressure hydrocephalus. The value of neuroimaging in the diagnosis of degenerative disorders is then discussed: Alzheimer's disease, frontotemporal dementias, dementia with Lewy bodies, dementia associated with parkinsonian syndromes, vascular dementias and mild cognitive impairment.