AIM:To investigate the expression of GAP-43 in the retina of normal rats during the development phase.·METHODS:RT-PCR method was used to detect the expression of mRNA in the retina of normal rats at the different age of postnatal. Immunohistochemical method was used to detect protein. And statistical analysis was performed on the experimental results.·RESULTS:The result of RT-PCR showed that GAP-43 continually rose before the 21st day of postnatal development and then reduced to a low level in the adulthood. With the development,the expression of GAP-43 got to highest at the age of P21 and then reduced to a low level in the adulthood. There was significance among different groups (P<0.01)·CONCLUSION:In the retina of normal rats and the time course of the critical period during development,GAP-43 mRNA and GAP-43 protein expression continually rise before the 21st day of postnatal development and then reduce to a low level in the adulthood.