One hundred and ninety-one brains were examined for lacunae and other cavitary cysts. Histologic and immunohistochemical studies by means of the peroxidase-antiperoxidase method for glial fibrillary acidic protein were carried out. Lacunae are small cavitary softenings observed on pathological examination and must be differentiated from cribriform cavities which are dilatations of perivascular space with or without impairment of the surrounding nervous tissue. A large number of cribriform cavities surrounded by rarefied perivascular nervous tissue and located in the basal ganglia can be accounted for pseudobulbar palsy or extrapyramidal syndromes.