d-Tubocurarine was used in an unselected series of 215 neonates undergoing surgery with only two cases of immediate postoperative respiratory difficulty. The neonate is more sensitive to d-tubocurarine than the adult but this sensitivity decreases during the neonatal period and may be partially explained by changes at the motor end plate and by a diminution in extracellular volume. Overdosage, potentiation by ether and antibiotics, hypothermia and failure to use anticholinesterase drugs are potent causes of immediate postoperative respiratory difficulties, which have been wrongly attributed to d-tubocurarine.