Objective To observe and evaluate the expression and significance of Nogo66 receptor (NgR) mRNA in adult ratsprime;optic nerve. Methods Optic and sciatic nerves of 8 adult rats were used to make the sections, which were divided into 3 groups: optic-nerve experimental group, sciatic-nerve control group, and optic-nerve negative control group. In situ hybridization was used to observe the expression of NgR mRNA in optic nerve and sciatic nerve. Results The expression of NgR mRNA in the 8 rats was positive in optic nerve and negative in sciatic nerve. The positive signals were arranged along the long axis of optic nerve. Conclusion The expression of NgR mRNA is positive in optic nerve while negative in sciatic nerve in adult rats, which suggests that the positive expression and distribution of NgR may be related to the poor regenerate ability of optic nerves. (Chin J Ocul Fundus Dis, 2005,21:246-248)