SUMMARY A patient is described who showed subacute dementia and ataxia and, finally, acute ascending polyradiculoneuritis. At necropsy, together with the cerebral and cerebellar lesions that are typical of Creutzfeldt-Jakob disease, the lesions of the spinal motor neurones, the spinal ganglia, and of the roots and peripheral nerves were analogous with those of the Guillain-Barre-Landry syndrome. The aetiological possibility is discussed either that this is a simple and unique association, or that the disorder is related to the virus nature of Creutzfeldt-Jakob disease.Creutzfeldt-Jakob disease is a progressive slow viral disorder in man caused by a transmissible agent whose precise nature remains obscure, as is the case with kuru in man, scrapie in sheep and goats, and mink encephalopathy, all of which are similarly subacute spongiform viral encephalopathies. The neuropathological features include spongy changes of the grey matter with neuronal loss and astroglial hyperplasia, affecting the cerebral cortex, striatum, and thalamus, with occasional degeneration of the cerebellum. According to the predominant clinical picture, Creutzfeldt-Jakob disease has been subdivided into several main types: (1) corticospinal or frontopyramidal form (spastic pseudosclerosis) with pyramidal tract involvement, and lower neurone involvement (amyotrophic type) (Davison and Rabiner, 1940;Allen et al., 1971); (2) Oppenheimer (1965). The presence of radiculoneuritis in the course of Creutzfeldt-Jakob disease has not been described (Kirschbaum, 1968;May, 1968;Van Rossum, 1968 The cerebral biopsy sample of the right frontal lobe revealed grey matter with intact structure and without neuronal loss or spongiosis. The white matter showed a low degree of astrocytic proliferation. Electron microscopy revealed focal cavitations of the neuropil due to vacuolation of some neurones and of their prolongations. The cavities were surrounded by a cellular membrane, and contained remains of nerve filaments and ribosomes (Fig. 1).At necropsy there was a moderate degree of cortical atrophy with an increased subarachnoid space. The main arteries were free of arteriosclerosis.The frontal cortex had the same normal appearance as in the biopsy sample. There were a large number of lesions in the parietal region, with a marked spongiosis and vacuolation of the neuropil in layers II and III. The neurones were degenerated in those zones, and there was a large gliosis with hypertrophic astrocytes (Figs. 2 and 3). The neurones were swollen in layers V and VI, with acidophilic cytoplasm, chromatolysis, and displaced nuclei. The subcortical white matter was normal. There was an obvious subependymal gliosis in the temporal cortex. The occipital region was normal.There was a moderate spongiosis in the thalamus, which was more intense in the subependymal zones and included reactive gliosis. There were many deposits of lipofuscin in the neurones of the basal ganglia. A loss of Nissl's bodies was observed in the pontine nuclei. The long tracts of the brain stem showed...