A study of 21 patients with Alzheimer's Disease and 25 with vascular dementia, the two most common forms of dementia, investigated language impairments in the dementia syndrome to see if analysis of language disturbances is helpful in differential diagnosis. Diagnostic assessment included a neurological examination, detailed medical history, screening laboratory tests, an investigation of the cerebrospinal fluid, a Luria-based neuropsychological test battery, analysis of language impairment, electroencephalography, and computerized tomography. Language testing included the Token Test and Short Aphasia Examination. The Alzheimer group, as a whole, had a slightly higher degree of dementia. All the functions tested were impaired in both dementia groups, although the degree of impairment was more severe in all areas in Alzheimer's disease. The language impairment correlated very significantly with the severity of dementia in both groups. It is concluded that different areas of language functions are affected in early Alzheimer's disease and vascular dementia, and in some patients, analysis of language might be helpful in a differential diagnosis of dementia. (MSE)