Creutzfeldt-Jakob disease (CJD) is one form of subacute prion diseases with spongiform encephalopathy. Hereditary, infectious and sporadic types of the disorder can be distinguished. The abnormal transformation of the prion protein, relevant in the normal synaptic transmission is considered as an important factor in the development of this disease. Gerstmann-Sträussler-Scheinker syndrome (GSS) and familial fatal insomnia (FFI) are the other diseases belonging to the same disease spectrum. The common feature of these disorders is that the different mutation of the same prion protein could result in different phenotypes and symptoms. CJD is considered as a neurologic disorder but the clinical symptoms and differential diagnosis of the disease are also relevant problems in psychiatry. Because of the early onset of dementia and the psychotic and delusive symptoms, the patients with CJD are frequently admitted to psychiatric wards. Recently worldwide public interest has been focused on prion dementias because of the possible human transmission of bovine spongiform encephalopathy in the UK. The diagnostic problems of our seven CJD patients diagnosed since 1991 in the catchment area of Szeged city are discussed in the view of recent findings of molecular biology, nosology, diagnostic and therapeutic problems of this devastating disease.