OBJECTIVE To evaluate the prevalence of cupping in arteritic anterior ischemic optic neuropathy (AAION) and nonarteritic anterior ischemic optic neuropathy (NAION). DESIGN Retrospective, observational case series. PARTICIPANTS Three hundred one patients. METHODS Review of clinical records and color fundus photographs. MAIN OUTCOME MEASURES Photographic and clinical interpretation of optic nerve appearance. RESULTS Ninety-two patients with AAION and 102 with NAION were included in the study. Disc photographs of 42 patients (48%) with AAION and 32 patients (31%) with NAION were available for reassessment. These were presented in a masked fashion along with a random sample of 27 disc pairs considered to be 'normal' and 27 disc pairs with 'established glaucoma' according to two examiners. Cupping was present in 92% of eyes with AAION secondary to giant cell arteritis and in 2% of eyes with NAION (kappa = 0.96; P < 0.001). CONCLUSIONS The end-stage optic disc appearance in AAION secondary to giant cell arteritis is cupping, whereas segmental or diffuse pallor without cupping is the typical disc appearance after NAION.