Advances in fetal therapy have led to the utilization of such techniques as intravascular transfusion of the Rh-affected fetus, bladder shunt placement in the fetus with obstructive uropathy, and percutaneous umbilical blood sampling. Fetal movement makes these procedures technically more difficult while increasing the risk of fetal injury. However, maternal sedation rarely results in adequate suppression of fetal activity. Thus we tested the sedative effects of intramuscular d-tubocurarine (3 or 1.5 mg/kg) or pancuronium bromide (0.3 mg/kg) injected into the fetal gluteal region under ultrasound guidance in conjunction with 70 invasive in utero procedures. Short-term paralysis of the fetus was induced in all cases. No deleterious effects of this technique were noted on initial examination of the neonates. Neuromuscular blockade was found to be a very useful adjunct to both diagnostic and therapeutic procedures involving the fetus.