The effect of peroral administration of "Cynkotox" (diethyl-dithio-carbamate, zinc salt) on the histoenzymatic activity of the brain was examined. 1.0 g of Cynkotox was given daily to adult Wistar rats over a period of 10 days (the per os DL50 for rats is 5200 mg/kg of body weight). The results have shown that chronic ingestion of large doses of Cynkotox may cause degenerative changes of neurons in various brain regions as well as alterations in the activity of various enzymes. The cerebral activities TPPase and of acP were evidently increased, whereas those of AChE, BuTJ and ATPase were markedly reduced. In some regions of the experimental rat brains. NsE activity was elevated in other ones some loss of NsE activity was noticed.