Bovine corneas were incubated in vitro with various lathyrogens in a medium containing radioactive sulphate. The effect of lathyrogens resulted in the decrease of the content of ester sulphate radioactivity in the corneal matter proportional to the concentration of lathyrogens in the incubation medium. Isolated glycosaminoglycans showed lower specific radioactivity after the action of lathyrogens on the cornea. By means of cetylpyridinium chloride-cellulose fractionation technique, it was found that preferential sulphation of galactosaminoglycans was inhibited whereas sulphation of glucosaminoglycans did not reveal any change. Tensile strength of corneal strips incubated in vitro in the presence of lathyrogens as well as the total collagen content in the corneal dry weight were not influenced by the action of lathyrogens.