A rabbit model of alkali burned cornea was made with 1 mol/L NaOH. On days 1, 3, 7 and 14 after the burn, changes in ultrastructure and the ruthenium red (RR) proteoglycan granules were as follows: (1) The epithelium and endothelium peeled off within day 1. In lightly burned cases, the epithelium regenerated on days 3-7; (2) The collagen fibers of corneal stroma became loose and irregular after the burn and began to recover with recovery of the cornea; (3) The RR proteoglycan granules decreased markedly after the burn, in light cases they increased on day 7 and gradually exceeded the normal amount, and then they reapproached the normal when the cornea was essentially recovered.