PURPOSE: To report a case of unilateral acute retinal necrosis after herpetic encephalitis CASE REPORT: A young man was referred with a chief complaint of blurred vision and pain of the left eye 1 month after herpetic encephalitis in the left frontotemporal lobe. The patient had multiple foci of retinitis in the retinal periphery associated with vitritis, blot retinal hemorrhage and retinal arteriolitis. The impression of acute retinal necrosis was confirmed by polymerase chain reaction of aqueous humor by detecting herpes simplex virus type 2; therefore, the patient received intravenous acyclovir. CONCLUSION: Herpetic encephalitis may be a risk factor for acute retinal necrosis. The virus may reach the eye by the trans-axonal route. Prophylaxis with acyclovir may be necessary after herpetic encephalitis to prevent acute retinal necrosis.