Objective To study the mRNA expressions of protein kinase C(PKC) and nerve growth factor (NGF) in rat sciatic nerve and the number ofaxons after phorbol-12-myristate-13-acetate (PMA) was injected into silicone chamber. Methods Forty-two SD adult rats were divided into six groups depending on the time of injury (1 day, 3 days, 1 week, 2 weeks, 3 weeks and 4 weeks). A 0.5 cm nerve was cut in doublerat sciatic nerves and “T” type silicone chamber was sutured. PMA at the concentration of 1×10-9mol/L was injected discontinuously into the right side of Ttype silicone chamber(PMA group) and saline was injected into the left side(control group). Nucleic acid in situ hybridization histochemistry technique and thecomputer imagine analysis were employed to detect dynamic changes of PKC mRNA and NGF mRNA in rat sciatic nerves. The number of axons was measured. Results The expressions of PKC mRNA and NGF mRNA increased after injury, and the expressions of PKC mRNA and NGF mRNA reached the peak 2 weeks and3 weeks after injury respectively in control group. The expressions of PKC mRNA and NGF mRNA in PMA group were significantly increased than those in control group 2,3 and 4 weeks after injury(Plt;0.01).The number of axons in PMA group significantly increased than that in control group(Plt;0.01). Conclusion PKC involved inthe expression of NGF mRNA and nerve regeneration after injury. During the regenerated course, PMA can promote the expression of NGF mRNA and the number of axons after injury.