The present study reports on the immunohistochemical distribution of S-100 antigen in non-nervous cell types within the human eye at light microscopy. In the cornea the antigen was confined to endothelial cells covering its posterior surface; the lens exhibited immunoreactivity restricted to the epithelial cells located beneath the anterior capsule. In the iris and ciliary body, S-100 was detected in stromal cells and epithelial cells of the pigmented inner layer in the former and inner epithelial cells bounding the posterior chamber in the latter.