Objective To study the effect and mechanism of Yaotongning（Capsule for relieving the pain in the lumbus） on lumbar intervertebral disc protrusion.Methods Totally 36 SD rats were randomized into sham operation group

model group and Yaotongning group with 12 in each.The silica gel film was used to press L5 nerve root to establish the models.The morphological changes of the nerve roots and the expressive changes of nerve growth factor（NGF） were observed. Results In the model group

there appeared the dyskinesia and the structural changes of nerve fibers of nerve roots

satellite cells

and neuron cells

and the NGF expression of nerve roots and soleus muscle was significantly increased（P<0.05 or P<0.01）.In the Yaotongning group

the motor function was significantly improved

the structures of medullary sheath of nerve root and neuron cells were intact

compared with the model group

the difference in NGF expression was significant（P<0.05 or P<0.01）.Conclusion Yaotongning relieves the motor dysfunction in rats with lumbar intervertebral disc protrusion.The mechanism may be inhibiting the NGF expression to repair the injured nerve roots.