AbstractTwo studies of motor response thresholds (RTs) to electricalstimulation at the wrist in newborns were done. Adult controls were employed. Strength‐duration curves for infant and adult RTs and adult sensory thresholds (STs) were plotted. RTs of infants are approximately 1.75 times higher than those for adults. Adult RTs are consistently 3 to 4 times higher than STs. Test‐retest reliabilities were satisfactory. RTs of half of the newborns were notably variable. No relationship between RT variability and stages of the neonatal wakefulness‐sleep cycle could be established, but RTs were significantly, although not markedly, higher during rapid‐eye‐movement (REM) episodes than during nREM. For evoked potential studies with newborns it has been decided to use as a stimulus a constant‐current square‐wave electrical pulse of 0.5 msec duration at RT during nREM sleep.