Infection of the eye following inoculation of herpes simplex virus on the skin of the snout was monitored using slit lamp examination of the eye, isolation of virus from eyewashings and identification of virus antigens in whole corneal epithelial sheets by peroxidase-antiperoxidase staining. Infection of the eye was prevented by removing a section of the sensory nerves which supply the inoculation site. This provided evidence that spread from the skin of the snout to the eye occurred via the nerves.