We identified retinal ganglion cells undergoing apoptosis, a form of programmed cell death, in an eye of a 70-year-old man with anterior ischemic optic neuropathy. The TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin end nick labeling) staining and the presence of condensed, fragmented nuclear bodies were used to identify apoptotic cells. Examination of TUNEL-stained retinal sections revealed occasional cells in the ganglion cell layer with pyknotic nuclei and brown reaction product, representing positive staining for chromosomal DNA breaks. Positive cells were sparsely distributed, consistent with the limited time in which apoptotic cells are identifiable before they are removed. The most likely explanation for these results is that injury to the retinal ganglion cell axon induces apoptosis. To our knowledge, this is the first report of human retinal ganglion cell apoptosis in an acute optic neuropathy.