A 13-day-old lowland gorilla died from a generalized herpesvirus infection shortly after the onset of clinical signs. The pathologic-anatomical findings were compatible with those described for generalized herpes simplex infection in the human neonate. Electron microscopic examination of lung tissue revealded the presence of herpesvirus which was identified with the fluorescent antibody technique as Herpes simplex virus type 1. Tests with related sera of the herpes group (varicella, herpesvirus-B) revealed no specific immunofluorescence.