Abstract: A specially designed electrode was implanted on the common peroneal nerve trunk of the rabbit.with the rabbit unanesthetized and unbound,relati-vely free movement being permitted, various elements (A—C) of the evoked compound action potential and the autogenic action potential can be recbrded stably and precisely within a long period of time.In this study we discovered that, it was not the fastest element of compound action potential that appeared first during the course of gradual increment of the stimulus of intensity.