The presence and distribution of alpha B-crystallin in the anterior segment of human, monkey and bovine eyes was investigated immunocytochemically. In all three species the most intense staining was seen in the lens and in the nonpigmented and pigmented epithelial cells covering the tips of the pars plicata of the ciliary body. The staining intensity of the ciliary epithelial cells was comparable to that seen in the lens fibers. Strong labeling was also found in the corneal endothelium. In bovine eyes the presence of alpha B-crystallin in lens, ciliary epithelium of the pars plicata and corneal endothelium was also shown by biochemical analysis using SDS-PAGE and immunoblotting.