This article relates a case of subacute sclerosing panencephalitis (SSPE) with special characteristics. The patient was a young male, eight years old. The disease progressed slowly over a period of several years terminating in death six years ofter the initial symptoms. Histopathologic examination revealed an encepahilitic process in evolution, with microgranulomes, perivascular inflammatory infiltrates, areas of neuronophagia, and intranuclear acidophilic inclusions in oligodendroglial cells. The cerebral white matter presented massive areas of demyelination, with astroglial cells undergoing an abnormal hyperplastic reaction with great nuclear atypias. This case, therefore, presented the histopathological picture of a chronic viral infection of several years' duration. Since it has been demonstrated already that viruses of the papova group may play a role in SSPE, it is possible that in this instance there may have been participation by papova viruses, due to the intense astroglial atypias found in the demyelinated areas.