A cumulative dose-response curve for d-tubocurarine based on body weight was determined for 44 infants and children 1 day to 7 years of age during halothane, nitrous oxide and oxygen anesthesia. Depression of thumb adduction was measured. Age difference did not affect the mean dose-effect response. Infants less than 10 days old, however, showed the wideest deviation of responses. When the effect of d-tubocurarine is determined by twitch response, infants and children are more resistant to d-tubocurarine and recover faster than adults from similar levels of neuromuscular depression. Monitoring of neuromuscular function by train-of-four stimulation proved as useful as it is in adults.