A method for quantitative analysis of the electromyographic interference pattern (IP) was carried out before and after phenol motor point blocks. Clinical evaluation for the spasticity was based on Ashworth scale before and after the blocks. Eight children with cerebral palsy and two children with traumatic brain injury were studied. The number of turns per second (NT) and the mean amplitude change between successive turns (MA) were obtained with recordings from the gastrocnemius muscle with surface electrodes at constant level of voluntary contraction for 10 times. The mean percentage differences in mean NT and mean MA between blocked and pre-blocked muscle were 59.2% (P<0.01) and 22.8% (p<0.01), respectively. The mean difference in Ashworth scale was grade II (p<0.01). A better correlation was noted between the differences of NT and the differences of Ashworth scale, than between differences of mean MA and differences of Ashworth scale. The mean NT correlated well to the Ashworth scale, indicating a close correlation between the mean NT and spasticity. All of the patients after motor point block revealed decreased mean NT and Ashworth scale. We concluded that quantitative EMG analysis helps evaluation of clinical status after treatment of phenol motor point block for the spasticity.