We compared clinical features in three groups of pathologically defined patients evaluated for dementia during life: (i) Alzheimer's disease (AD); (ii) Lewy body variant of Alzheimer's Disease (LBV), with Lewy bodies (LB) and AD; (iii) diffuse Lewy body disease (DLBD), with LB alone. All three groups had similar initial cognitive symptoms. LBV and DLBD had Parkinsonian signs, though resting tremor was extremely rare. Delusions and hallucinations were relatively more frequent in LBV and DLBD than in AD. On neuropsychological testing, the LBV group had relatively greater impairment than AD on visuospatial and executive tests. LB therefore contribute to the clinical picture of dementia.