Acute herpes simplex encephalitis (HSE) carries significant morbidity and mortality even after early treatment with antiviral agents (7). As well as causing acute neurological disease, Herpes viruses are associated with relapsing--remitting (Varicella--Zoster, Epstein-Barr) and chronic (Rasmussen encephalitis) disease processes (1). A two-year-old girl developed acute HSE which was followed by a 10-year neurologic illness characterised by asymmetric spastic tetraparesis, pseudobulbar palsy, the opercular syndrome of Foix-Chavany-Marie (4) and seizures. The neurological signs remained static until the child died suddenly 12 years after disease onset. Neuropathologic examination demonstrated active chronic encephalitis. Herpes simplex virus (HSV) DNA was recovered from formalin-fixed paraffin-embedded brain tissue. This case provides additional evidence for the development of chronic neurological disease attributable to persistence of herpes simplex virus type 1.