Purkinje cells from five autopsy cases (a premature newborn infant, a GM1-gangliosidosis, an olivo-ponto-cerebellar atrophy, a multisystem atrophy involving the spinal cord and the brain stem, and a woman of 82 years) were studied using the Golgi impregnation technique. The results were the following: (1) the Purkinje cells showed different abnormalities in each case; (2) the dendrite and cell body showed not only involutive/degenerative but also progressive/plastic changes at the same time in some cases; (3) Purkinje cells which appeared normal in routine histological preparations showed, in some cases, abnormalities of the dendrite and cell body; (4) the abnormality common to the five cases was the loss of branchlet-spines and/or spiny branchlets, probably resulting in loss of the granule cell-Purkinje cell connection. It is discussed that the Golgi technique as applied to morbid human material will be an indispensable tool in the future for the analysis of disease processes on cellular and neurobiological bases.