The association of herpes simplex encephalitis and herpes simplex retinitis is rare in adults. The case presented indicates that the manifestation of retinitis after herpes simplex encephalitis is infectious and not immunologic in origin. Retinal infection results either from neuron-to-neuron transmission of viruses along the optic nerve or from recurrent viral infection. Treatment with acyclovir improves the otherwise rather poor prognosis of combined herpes simplex encephalitis and retinitis. In this case a second course of systemic treatment with acyclovir was effective.