Prion infections (transmissible sponhioform encephalopathies (TSEs)) cause brain damage of humans and animals with lethal outcome. These diseases can be hereditary and sporadic. Neuronal degenerative changes, vacuolization of neurons, proliferation of astrocytes in the brain cortex, stem and cerebellum of the brain after death of TSE patients have been shown by histological research study. Cellular prion (PrP C ) is needed for replication of pathological PrP Sc which can cause infection development depending on the level of PrP C production in the different tissues. PrP C is membrane surface glicoprotein, that has important function including antioxidant, antiapoptotic protection, transport of certain ions and others. PrP C conversion into the pathological form leads to changes of the molecule conformation, consequently, to loss its physiological functions with a violation of metabolism in general.The localization of PrP C in the cerebellum of rats of different ages has been demonstrated. The cellular prion was found in the cerebellar cortex, particularly in neurons of the molecular and granular layers, as well as in Purkinje cells. The localization of PrP C was unchanged under age-related changes of the cerebellum. The amount of cellular prion was determined by the immunohistochemical and dot blot analysis methods. In particular, the PrP C level was the highest in cerebellum of six months rats and the lowest in cerebellum of thirty months animals.