A neuropathological examination was performed on a patient with parkinsonism induced by prolonged exposure to a mixture of aliphatic hydrocarbons, mainly n-hexane and halogenated compounds. The patient developed a rapid-course disease that progressed even after with-drawal from the toxic exposure. Pathological examination and immunohistochemical analysis of the brain revealed severe and widespread dopaminergic neuronal loss, associated with severe gliosis, in the substantia nigra, and almost complete loss of tyrosine hydroxylase immunostaining in the striatum. No Lewy bodies were detected. Neuronal loss was also observed in the periaqueductal gray matter, locus ceruleus, and pedunculopontine nucleus. These changes, combined with the moderate anemia due to marrow suppression, and the mild axonal neuropathy observed in vivo, are suggestive of a hydrocarbon toxic insult.