Objective To evaluate the effect of chondrotinase ABC treated decelluarilzed nerve allograft on repairing never defects in rats.Methods Nerve allografts were treated with chondrotinase ABC and decellurized using chemical detergents.The allografts were employed to repair 15 mm sciatic nerve defects in rats in the experiment group (Group A).The nerve gaps were bridged by decellularized nerve without chondrotinase ABC treatment in Group B and by autografts in Group C.Pain reaction was tested at 8 weeks and 12 weeks postoperatively.Electrophysiology,muscle wet weight of the gastrocnemius-soleus complex and the myelinated fiber density of the regenerated nerve were quantified at 12 weeks postoperatively.Results The proportion of pain reaction recovery in Group A was higher than that in Group B and Group C at 8 weeks postoperatively.At 12 weeks postoperatively,pain reaction test was positive in all the rats in Group A and Group C,whereas most of but not all the rats in Group B had a positive pain reaction.There was no significant difference in muscle weight of rats in Group A and Group C at 12 weeks.The myelinated nerve fiber density at the proximal 5 mm of the graft was higher in Group A than in Group C,whereas no significant difference was seen at the distal 10 mm of the graft.The myelinated nerve fiber density was slight lower in Group A than in Group C in the tibial nerve division 5 mm distal to the graft.Compound muscle action potential amplitude showed no differences between group A and group C.Nerve conduction velocity was slower in Group A than in Group C.The aforementioned indexes in Group B were inferior to Group A and Group C.Conclusion Chondrotinase ABC treatment facilitates axons to enter the decelluarilzed nerve allograft.This reduces target organ reinnervation time and improves functional recovery. Key words: Nerve regeneration; Chondroitin sulfate; Chondroitin sulfate proteoglycans; Ace]lular nerve