Two patients were described with a five to seven-year history of primary progressive non-fluent aphasia. One patient developed atypical trascortical motor aphasia with marked anarthria, which has led to mutism. Magnetic resonance (MR) imaging showed lobar atrophy of the frontal lobe accentuated in the bilateral superior frontal gyri, the left middle frontal gyrus, the left anterior cingulate gyrus and the left operculum with some extension into the left temporal lobe. Single photon emission computed tomography (SPECT) scans demonstrated a decrease of regional cerebral blood flow (rCBF) in the atrophic site. The patient was clinically and neuroradiologically diagnosed as having Pick's disease. Another patient presented with atypical Broca's aphasia, which has worsened with slowly progressive right hemiparesis. Mitigated, sometimes complete, echolalia was also observed. MR imaging and SPECT scans showed mild atrophy and a decrease of rCBF in the left perisylvian region involving the frontal operculum, while a positron emission tomographic study disclosed diffuse hypometabolism in the left hemisphere. We pointed out that the features of primary progressive aphasia were frequently atypical in the light of classical classification of aphasia and that non-fluent aphasia might be observed even in the early stage of cortical degenerative processes.