A case of neuronal intranuclear hyaline inclusion disease (NIHID) is described. The patient was a 26-year-old man who died of a progressive neurologic disorder, the onset of which occurred at the age of 11 years. Clinically, the disease presented as juvenile parkinsonism, and pathologically it was characterized by multiple-system degeneration in conjunction with the ubiquitous presence of intranuclear hyaline inclusions in neurons of the central and peripheral nervous system including the autonomic ganglia. Smaller and less eosinophilic intranuclear inclusions were also present in a small number of glial cells. The neuronal inclusions emitted a strong yellow-green autofluorescence under ultraviolet light and were composed of filaments 10-15 nm in diameter. The glial inclusions also consisted of similar filaments but their autofluorescence could not be determined with certainty because of their small size and background autofluorescence. A review of the literature revealed 19 similar autopsy cases up to 1987. Since the clinical presentation and distribution of neuronal loss as well as the characteristics of the inclusions showed some differences among the cases, some authors speculated that NIHID represented more than one variant of a multiple-system degenerative disease. However, about half of the reported cases had favorable sites of neurodegeneration, such as the pallidum, substantia nigra, motor nuclei of the brain stem, anterior horn cells, Clarke's column and spinal ganglion as well as similarities among the inclusions. Thus, there seems to be a discrete group among cases of NIHID.