This paper is a summary of a series of researches carried out in this laboratory since 1979 on the afferent fibers responsible for the acupunctureanalgcsia. 1. The analgesic effects produced by activation of different groups ofafferent fibers during electro-acupuncture were observed in the rabbit. Thejaw-opening reflex induced by noxious electric stimulation to the proximalperoneal nerve was used as a pain response. The distal portion of the samenerve was stimulated electrically with repeated pulses (5Hz) to simulate electro-acupuncture of the points. The results indicated that the smaller the fibers