Objective To study and compare the effect of normal end-to-side neurorrhaphy and modified spiral end-to-side neurorrhaphy in an animal model,and provide basis for choosing a better nerve repair method in clinical application.Methods Sixty rats were randomized into 3 groups (A,B and C,n =20).In all groups,the right peroneal nerve was transected at the level 3 mm distal to its take-off from the sciatic nerve.In group A,the distal end of the injured peroneal nerve was cut at an angle of 90 degrees,and sutured in an endto-end fashion.In group B,the distal end was transected at an angle of 45 degrees,and sutured in an end-toside neurorrhaphy fashion with an epineurial window in the donor nerve.In group C,the distal end was cut at an angle of 10 degrees,and sutured in a modified spiral end-to-side neurorrhaphy fashion with more epineurial windows in the donor nerve.Histological,electromyographic,muscle wet weight analysis,myelinated nerve counts and neuronal tracing with Dil were performed at the end of 8 weeks postoperatively.Results In group C,the recipient peroneal nerve had regenerated better than that in group B.The difference between group C and group B was significant (P ＜ 0.05),while there was no significant difference between group C and group A (P ＞ 0.05).Conclusion The modified spiral end-to-side neurorrhaphy can enhance axonal sprouting from the donor nerve and improve the functional recovery.The donor nerve epineurial window surface area,the contact configuration and the distal end area of the injured peroneal nerve are the important factors to the end-to-side coaptation model.