The purpose of this study was to determine the validity and reliability of the Power Walker® 610(PW) pedometer for step counting in children. The study sample was composed of 30 boys and 22 girls, from 8-13 years old. Participants were equipped with both a PW and a Digiwalker® SW-200(DW) pedometers and walked 400 m around an outdoor athletic track at a self-selected speed, and on a treadmill at 3, 4 and 5 km/h for 5 minutes at each stage. Direct observation(DO) of the number of steps was performed by two observers and used as the criterion measure. There were significant differences for step counting between DO and PW while treadmill walking at 3 km/h. The coefficient of intra-class correlation values remained high for both pedometers and the coefficient of variability proved to be stable. The PW is a valid and reliable device for assessing a continuous level of walking steps inchildren.