Plasma bupivacaine levels were measured in 47 women undergoing extradural Caesarean delivery. They were divided into four groups according to the following dose regimens using 0.5% bupivacaine. Group A were given a bolus of 20 ml with increment after 20 minutes. Groups B and C were given 10 ml initially with further increments if required at 10 minutes (group B) and 20 minutes (group C); Group D consisted of patients who had an extradural block extended for emergency Caesarean delivery. In the elective groups the highest and most rapidly achieved values were associated with group A and the lowest levels found in group C. The highest levels of all were found in the emergency group. The investigation indicates that slow controlled induction of extradural anaesthesia for Caesarean section greatly reduces the risk of local anaesthetic toxicity.