We investigated the effects of various culture conditions on the growth of normal human corneal endothelial cells in culture. Falcon Primaria tissue culture plastic was found to provide a more suitable surface for endothelial cell growth than the conventional Corning tissue culture plastic. Also, media containing 10% fetal bovine serum and 5% calf serum (complete media) facilitated the growth of human cells better than those containing Nu-serum. Supplementation with epidermal or fibroblast growth factor (10 and 100 ng/ml) to the complete media had no effect on human endothelial cell growth. Chondroitin sulfate at low concentrations (100 micrograms/ml to 1 mg/ml) also showed little effect. At high concentrations (13.5 and 25 mg/ml), however, chondroitin sulfate significantly promoted human corneal endothelial cell growth during a 1- to 2-week incubation period. From the 37 cultures initiated, outgrowth from explants appeared within 3 to 7 days. Cells were polygonal in shape and, at confluency, formed a continuous monolayer. We attained a success rate of 87% (7/8) growing primary cultures from donors under 20 years of age and a 59% (17/29) success rate from older donors.