The influence of cutaneous electrical stimulation (CES) on reaction time (RT) was examined in 8 normal subjects. CES, wherever applied, generally increased RT, and only affected the pre-motor component of RT. Compared to RT without CES, a stronger effect of CES on RT prolongation was obtained from the skin over the antagonistic muscles, a weaker one from that over the agonistic muscles and a moderate effect from the skin of nonresponding part of body. Possible neurophysiological mechanisms of these phenomena were briefly discussed.