We report an atypical case of acute retinal necrosis (ARN) with a subacute course and relapses lasting for more than 4 years in an apparently immuno-competent 71-year-old female who had been followed for 4.5 years for recurrent retinochoroidal lesions with transient exudative retinal detachments and areas of consecutive chorioretinal atrophy. The diagnosis of varicella-zoster virus (VZV)-induced ARN was finally made on the basis of anterior granulomatous uveitis, typical retinal necrosis and the detection of anti-VZV antibodies in the aqueous humor. A widespread lumbar zoster dermatitis, cutaneous anergy and depressed in vitro lymphocyte activation indicated depressed cellular immunity. Absolute and relative numbers of B lymphocytes were increased. It is suspected that depressed cellular immunity and maintained B cell function might possibly be at the origin of ARN. The protracted course of ARN in this patient also suggests that the dysregulation of the immune system has probably existed for a long time.