We studied two blind eyes enucleated during the active phase of the acute retinal necrosis syndrome. Both eyes showed similar histopathologic findings of necrotizing retinitis, retinal arteritis, and optic neuropathy. A virus morphologically consistent with a herpes group virus was found on electron microscopy and immunocytopathologic stains showed this virus to be varicella zoster in both cases. Varicella zoster virus was cultured from the vitreous of one of the eyes. We conclude that varicella zoster virus retinal infection is a cause of the acute retinal necrosis syndrome.