To study electroretinographic (ERG) changes in the course of human immunodeficiency virus (HIV) disease, 42 eyes without retinitis were examined twice or more. During 9.6 months of mean observation time the visual acuity did not change. We found progressive functional impairment for the first, second, and third neurons of the visual pathway: the pattern-ERG amplitude (retinal ganglion-cell function) decreased by 11%, the b-wave amplitude (bipolars mediated by Müller cells) decreased by 13%, and the a-wave amplitude (dominated by rods) diminished by 21%. The flicker amplitude (dominated by cones) decreased by 20%. All of the latter four changes were significant (P < 0.02). Damage to the retina in HIV infection cannot solely be explained by visible changes in HIV retinopathy.