The authors illustrate the spectrum of clinical and imaging patterns in primary progressive aphasia (PPA), a syndrome of slowly progressive speech and language impairment occurring with neurodegenerative disease. Although PPA presents with relatively isolated impairment in language, many patients progress to global cognitive or behavioral dysfunction. The syndrome may be associated with frontotemporal dementia (FTD)- or Alzheimer disease (AD)-type changes. Authors describe the clinical presentation in three cases of PPA and analyze the pattern of cerebral atrophy in each case with voxel-based morphometry. Two patients presented with nonfluent progressive aphasia. Subtle differences in the clinical features were suggestive of FTD in one case and AD in the other. Neuroimaging revealed a predominance of frontal atrophy in the first case and temporo-parietal atrophy in the second. The third case presented with the syndrome of semantic dementia and showed the typical behavioral problems associated with FTD and a pattern of left-greater-than-right temporal atrophy. Different clinical syndromes in PPA are associated with different patterns of atrophy. In the future, combined analysis of imaging and clinical characteristics may allow more accurate etiologic diagnosis.