Parvalbumin-immunoreactive dystrophic neurites and aberrant terminal sprouts associated with senile plaques, together with preserved density of parvalbumin-immunoreactive neurons, were found in the cerebral cortex of two patients with Alzheimer's disease, one of them familiar, in which a biopsy of the left frontal lobe was carried out for diagnostic and counselling purposes. These findings suggest that, although parvalbumin-immunoreactive cells are relatively resistant to degeneration in Alzheimer's disease, parvalbumin-immunoreactive neuronal processes can degenerate in some cases of Alzheimer's disease.