We have recorded the afferent unit discharges and using it as an index, measured the locations and the volumes of nine acupoints, such as Neiguan and Shaoshang, which are innervated by median nerve. We have also investigated the relationships between electric needling sensations and afferent fibres of different groups as well as manual needling sensations by means of analysing power-spectrum of the unit discharges with FFT. It has been found that the fibres of Group II and Group IV convey numbness and soreness, respectively. The fibres of Group III relates to the conduction of heaviness and distention closely.