Objectives: To observe ultrastructural changes of the corneal endothelium and to assess the significance of the changes after irrigation and aspiration(I/A) of the anterior chamber in rabbits. Methods: Corneal thickness and intraocular tension were measured and the ultrastructure of corneal endothelium was observed in scheduling times following I/A. Results:Obvious injury of the membrane structure of corneal endothelium was viewed with scanning electron microscope 1 day after injury. Transmission electron microscope revealed marked swelling of the organelles, increasing vacuoles in the cytoplasm and swelling, denuding, dissolving of the cellular nuclei 3 days after injury. The lipoballs resulted from aggregation of lipid in the cellular membrane adhered to the defect region of endothelium 5 days after injury. Scanning electron microscope displayed marked sign of migration of the corneal endothelium 7 days following injury. The corneal endothelium was heteromorphic and the degeneration of the epithelium occurred. The corneal thickness gradually increased and directly related to the degree of the corneal muddiness. The corneal thickness increased and the injury of endothelium aggravated when intraocular tension increased. Conclusions:The results of ultrastructural examination indicated that destruction of the corneal endothelium following injury seems to be a consequential sequel. Dynamic corneal thickness measurement contributes to the judgement of degree of corneal endothelium injury. Control of intraocular tension is one of the important methods for preventing secondary injury of the corneal endothelium.