The EEG changes in acute optic neuritis in children are described. The EEGs are essentially normal in unilateral cases of optic neuritis. In contrast, bilateral optic neuritis with significant visual deficit produced occipital slowing, at times appearing very rapidly. The slowing correlated with the degree of visual deficit and improved with the improvement of visual acuity. In two cases, permanent visual deficit remained and in these, occipital spikes were superimposed on pre-existing slow waves. These clinical observations are discussed in light of the deafferentation hypothesis proposed from other clinical and experimental data.