Acute retinal necrosis syndrome (ARN) is a rare and potentially visually devastating syndrome that occurs in otherwise healthy patients. We present ten cases seen at the Veterans General Hospital-Taipei from 1985 to 1990. All patients were male. The onset occurred at the age of 19 to 71 years (43.7 in average). All except one case were unilaterally involved. Among the 11 diseased eyes, 4 eyes of 3 cases recovered a fair vision and the rest 7 eyes nearly lost vision. There was nearly total blindness in the earlier cases. Retinal detachment occurred in 7 cases (70%). Intraocular antibody production by determining the Goldmann-Witmer coefficient was calculated in 9 cases. It was found significant elevation of varicella zoster virus in 8 cases and of herpes simplex virus in 1. Although all patients appeared healthy with nothing particular in the past history, a decreased reaction to delayed type hypersensitivity as performed with skin anergy panel test was found in 4 of 5 performed patients.