Language disturbances may appear early in the course of dementia of the Alzheimer type (DAT) and become frequent as the disease progresses. Moreover, the presence of language impairment seems to be associated with a faster cognitive and functional decline. The profile of the linguistic changes depends on the stage of the disease, with anomia and impairment in verbal fluency tests being early and prominent features. In the initial and intermediate phases of the disease there is a marked lexical and discourse deficit, characterizing a semantic impairment, with preservation of syntactic and phonological abilities. This semantic deficit is probably secondary to pathological involvement of the temporal neocortex, an anatomical region related to lexical retrieval. In later stages, all language components become involved.