In order to elucidate in vivo neuronal cell death in the retina, and involvement of NF-κB in this process, we studied the degeneration of retinal ganglion cells (RGCs) and the activation of NF-κB after transection of the optic nerve of adult rat at 5 mm from the eyeball. The morphology of dying ganglion cells in the retinal ganglion cell layer was observed by light and electron microscopy, the activation of NF-κB was investigated immunohistochemically. Seven and 14 days post-axotomy, dying cells contained pyknotic nuclei. The death of retinal ganglion cells involved apoptosis, activation of NF-κB (p50 and p65) was prominent in a time dependent manner. We observed axotomy-induced NF-κB activation, which may mediate apoptosis of retinal ganglion cells.