Objective To observe the enzymic histochemical and ultrastructral changes of cryopreserved human retina. Methods To compare the activity of lactate dehydrogenase (LDH)， succinate dehydrogenase (SDH) and ATPase in cryopreserved retina with those in fresh retina and to observe the histological and ultrastructural changes of cryopreserved retina. Results There was no statistical difference between the activity of LDH，SDH and ATPase in fresh and in cryopreserved retina. Histologically, in the cryopreserved retina, fluid in neural fiber and outer plexiform layers, as well as in cone and rod layer, was sligthly more than normal. The ultrastructure is normal except that the mitochondria was swollen in different degree. Conclusion Cryopreservation may be an effective method for keeping the retinal cells alive for a long period and might free the transplantation from dependance on aviability of fresh dornor tissue. (Chin J Ocul Fundus Dis，2000，16：139-212)