Two cases of presenile dementia were presented. Both showed "stehende Redensarten" and aphasia. Histopathologically, besides Pick features--temporal lobe atrophy, fibrillary gliosis of the temporal white matter and neuronal loss in the 2--3 cortical layers--, Alzheimer features--neurofibrillary tangles and granulo-vacuolar degeneration--were found in both cases. But no senile plaques were found. Pseudocalcerous deposits were observed in the cerebral cortex, basal ganglia and cerebellum. Atypical cases with both Pick's and Alzheimer's diseases in the literature were classified into four groups according to the extent of the features of each disease. Sensory aphasia, which is relatively unusual in Pick's disease, was correlated to the atrophy of left T1, and similar cases in the literature were reviewed.