Introduction: Anticipation of voluntary motor activity leads to feed-forward activation of sympathetic nervous system. No-go signal serves as an experimental paradigm for studying anticipation of voluntary motor activity, where the intended motor task needs to be suspended. It is hypothesized that no-go signal may induce sympathetic activation required for subject’s preparedness for discontinuation of motor command. The present study was designed to evaluate the effect of no-go signal on sympathetic vasomotor function in a motor task performing situation. Methods: Fifteen healthy subjects were asked to respond to either “YES” (go) or “NO” (no-go) commands. Subjects either had to press the hand grip dynamometer with maximum contraction or ignore in accordance to command structure. These were labeled as Actual Contraction (AC) and no contraction (NC) respectively for go and no-go commands. The surface EMG was recorded from ipsilateral forearm and photo-plethysmogrpah (PPG) signal was recorded from the middle finger of the contra-lateral hand in sitting posture. The PPG amplitude (pulse volume amplitude, PVA) was used as a measure of sympathetic vasomotor function. The decrease in PVA of the PPG wave was taken as the measure of sympathetic activation. The baseline EMG and PPG were recorded for 2 min. Average of 2 min PPG amplitudes at rest was considered as baseline amplitude. The PPG and EMG recordings were acquired for 30 sec following both the commands (go/no-go). For AC it was ensured that subjects maintained contraction for 30 sec. Both the go and no-go commands were given three times in random fashion to each subject. The 30 sec PPG records during both AC and NC were further analyzed for PPG amplitudes averaged in 10 sec bin. The amplitude value of three records was averaged for the purpose of analysis. The data was analyzed using paired t test and results are expressed as mean ± SD. Results: The averages of 10 sec PVAs decreased significantly during AC (280.7 mv ± 103.6 to 122.7 mv ± 65.56; p<0.001; decrease of 56.3 %). The PVAs of initial 10 sec of NC were found to be significantly decreased (280.7 mv ± 103.6 to 191.4 mv ± 110.6; p ≤ 0.001; decrease of 31.81 %). The % decrease of PVA was significantly less during NC compared to AC (p<0.001). However even during no-go signal subjects showed 31.8 % of residual activity. The no-go signal alone showed a sympathetic activation of 56.5 % {(31.8/ 56.3)X100} when compared to AC. Conclusion: In the present study no-go signal for voluntary motor activity initiated sympathetic drive to vasculature in a situation where motor task was not performed. This reflects that nearly 50 % of sympathetic activation occurs due to readiness, even before the initiation of motor activity. Therefore even to execute no-go command a substantial sympathetic activation is required. This appears to operate through feed forward mechanism.