Objective To investigate the mRNA expression of ciliary neurotrophic factor on the retina during injury and repair of optic nerves in rats. Methods Thirty-five healthy SD rats were randomly divided into 3 groups: 5 in the control group, 15 in the simply transected optic nerve group and 15 in the optic nerve-sciatic nerve anastomosis group. The simply transected and optic nerve-sciatic nerve anastomosed models were set up, and the retinal tissues of all of the rats were taken out after 3, 7 and 14 days, respectively; and the mRNA expression of CNTF in the 3 groups were observed by semiquantitative reversal transcription-polymerase chain reaction method. Results A minimum expression of CNTF mRNA was found in the retinae of the control group, and the increased rates of expression were found in the retinae of the simple transection of optic nerve group with the increase rate of 100%, 594%, and 485% on the 3rd, 7th, and 14th day respectively after the operation, while in optic nerve-sciatic nerve anastomosis group, the increase rates were found to be 258%, 752% and 515% on the 3rd, 7th, and 14th day respectively after the operation. Conclusion Retinal neurons can respond to axonal reaction of retinal ganglion cells by up-regulate endogenous CNTF after the injury of the optic nerves, which may provide a theoretic base for the application of the exogenous CNTF. (Chin J Ocul Fundus Dis，2004，20：355-357)