We have summarized relevant literature on the patterns of memory deficit found in Alzheimer's disease, the focal lobar atrophies (semantic dementia and dementia of frontal type) and three forms of subcortical dementia (progressive supranuclear palsy, Huntington's and Parkinson's disease). We have stressed an approach based on the joint principals of cognitive neuropsychology and applied neuroanatomy. Alzheimer's disease results in a severe deficit in the establishment of new episodic memories which reflects the perihippocampal locus of the early pathology. In semantic dementia, there is profound progressive and relatively pure loss of semantic memory associated with focal left temporal neocortical atrophy. By contrast, in the subcortical dementias the major impairments are in working (immediate) memory and retrieval of information from longer term memory stores, deficits which reflect dysfunction of frontostriatal systems.