A case of peculiar form of Creutzfeldt-Jakob disease — the subacute disseminated encephalo-myelopathy one — is reported. The diagnosis was ascertained by necroscopic study. The clinical and electroencephalographic aspects are analysed. The patient here concerned, a man aged fifty two, during the clinical course of the disease showed stupor, decorticate posture, myoclonic jerks, epileptic seizures, muscular wasting in the left leg, exaggerated tendon reflexes in the face, tendon reflexes not elicitable in the legs. The electroencephalographic findings, during the downhill course of the disease, showed a pattern of irregularly depressed background rhythm with the periodic synchronous high voltage wave. The post-mortem findings revealed mild atrophy of the brain and the histological study revealed neuronal degeneration, astroglial hypertrophies and status spongiosus. The microscopic examination showed that the areas most affected were the frontal and occipital lobes, the basal nuclei, the mesencephalon, the pons and the anterior horns. In the cerebelum the granular cells were reduced. Pathogenetic and etiological considerations remained inconclusive, but the slow-virus concept applicable to other neurological diseases (Kuru, subacute sclerosing leuco-encephalitis) should not be dismissed from etiopathogenetic considerations of Creutzfeldt-Jakob disease.