Human corneas were analyzed for glycosaminoglycans during various stages of embryonic development and at different postnatal ages. The development and aging of the cornea was accompanied by a transient increase of glycosaminoglycan hexosamine up to 2 years of age and thereafter by a stepwise decrease to a value which seemed to be constant in all age groups. Keratan sulphate formed a minor part of glycosaminoglycans in fetal, premature and newborn corneas but it predominated in older corneas. The development of the cornea was characterized by a decrease in sulphation of chondroitin sulphate. No hyaluronate was found in the fetal corneas available for this study.