Objective: The transmissible spongiform encephalopaties are characterized by vacuolization, neuronal loss, gliosis and deposition of a misfilded and Proteinase K resistant isoform of the prion protein (PrPSc) in the central nervous system. Methods, materials and patients: Paraffin-embedded tissue blot (PET-blot), immunohistochemistry (IHC) and Western blotting (WB) were combined to stydy the morphology and localization of disease related PrP in Danish patients with different subtypes of sporadic Creutzfeldt-Jakob disease, familiar Creutzfeldt-Jakob disease and Gertsmann-Sträussler-Scheinker disease. Results and conclusion: There was a good morphological and anatomical concordance between what was found with PET-blot and IHC in all patients. In some specific cases, the PET-blot was superior to IHC in sensitivity. to our knowledge, this is the first report where PET-blot analysis is applied to hereditary forms of human transmissible spongiform encephalopaties and compared with sporadic cases of Creutzfeldt-Jakob disease.