Measurement of motor nerve conduction velocity(MNCV) of the median and peroneal nerves was performed in 79 normal fullterm newborn infants and children up through the age of 329 weeks. They were divided into eight groups by age. The following study was undertaken to obtain the mean±S.D. and the regression equation of Y (MNCV) on X (age). The MNCV values of each group were compared with those of normal adults.