The sensitivity of the Mini-Mental State Examination (MMSE) was assessed in a sample of patients with dementia of the Alzheimer type or vascular dementia. The MMSE identified the majority of pts with diffuse cognitive impairment but did not discriminate between the two types of dementia. If failed to detect mild deterioration or forms in which only some cognitive functions were impaired. The test is therefore not sufficient for distinguishing deteriorated from non deteriorated pts, although it is still useful in mass screening or for a quick assessment of deterioration in the course of clinical neurological examination.