Histopathology of eye, optic nerve and brain was performed in a patient with typical signs and symptoms of dominant optic atrophy. He belonged to a previously-reported family of 152 members in which optic atrophy was demonstrable in 14 persons, and probably present in a further 8 cases. In the eyes, fibrosis of the retinal ganglion cell layer and disc was found. Ultrastructural examination showed a few remaining cells in this layer, heavy fibrosis and in particular a highly condensed inner limiting membrane. The optic nerves, the optic chiasm and optic tracts showed an increased content of collagen tissue and a decreased number of neurofibrils and myelin sheaths. In the lateral geniculate body there was massive loss of ganglion cells, fibrillary gliosis and a great quantity of fine granular lipid in the cytoplasm of the ganglion cells. No changes in the calcarine cortex were observed. Examination of the intracranial part of both vestibulocochlear nerves showed a decreased number of neurofibrils and myelin sheaths. It is concluded that the histopathological changes of the visual system are similar to those in Leber's disease, but less pronounced. The study confirms earlier theories that dominant optic atrophy is a primary degeneration of the ganglion cell layer in the retina, with ascending optic atrophy.