An electromyographic silent period appears prior to initiation of a reaction movement. In order to estimate the mechanism of the silence, the statistical properties of the EMG before the onset of the phasic discharge were investigated. The EMG activity was processed as a stochastic process, and the statistical properties were analyzed. It was found that the mean of the rectified EMG decreased from 100 ms before the onset of the phasic discharge. As to the relationship between the silence and the depression of the EMG activity, it was estimated that the depressing influence was so remarkable that the silent period was observed.