The clinical, neuropsychological and neuroradiological features of two patients affected by herpes simplex virus type 1 (HSV-1) encephalitis are described. An experimental study for the assessment of naming, recognition and description displayed in one patient a persistent significant impairment in naming living things. The other patient showed a failing "semantic memory" for the same categories, although a significant impairment emerged only for plants. In both patients, the late neuroradiological sequelae were localised mainly in the inferior and middle gyri of the left temporal lobe and in the left-side insula. In one patient, the right-side insula was also involved. The selective cerebral damage induced by HSV-1 is stressed and a correlation between the neuroradiological and neuropsychological findings is attempted. The stereotyped anatomical and neuropsychological changes lead to the belief that the virus may recognise, within the limbic system, particular cellular "strains" on the basis of their molecular specificity.