The localization of two small heat shock proteins, alpha B crystallin and 28-kDa heat shock protein (HSP28), was studied immunochemically and immunohistochemically in cerebral cortex of patients with Alzheimer's disease (AD) and control groups. By specific immunoassays for alpha B crystallin and HSP28, we found that the concentrations of alpha B crystallin are elevated in the temporal and frontal lobes, while those of HSP28 are elevated in the temporal, frontal, and parietal lobes in the AD brains. Immunohistochemically, alpha B crystallin was localized in astrocytes and oligodendrocytes, while HSP28 was present in degenerating neurons in the cerebral cortex of both AD and control brains. However, alpha B crystallin-immunoreactive astrocytes and HSP28-immunoreactive degenerating neurons were more frequently observed in AD brains. The immunoreactivity for HSP28 was also found in the senile plaques in the AD brains. These findings suggest that the increased accumulations of these small heat shock proteins appear to be part of reactive processes of glial cells and neurons under pathologic conditions.