The effects of extradural and general anaesthesia on the adrenocortical response to elective or emergency Caesarean section were studied in 72 patients. Maternal plasma concentrations of cortisol were measured before surgery, at delivery, and 30 and 60 min after skin incision. Umbilical vein and artery plasma cortisol concentrations at delivery were determined also. Maternal plasma cortisol concentrations in patients receiving extradural anaesthesia did not change significantly from control at any of the time intervals. In the general anaesthesia group concentrations were significantly increased from control, at 30 and 60 min after skin incision for elective Caesarean sections, and at 60 min after skin incision during emergency surgery. There were no significant differences between the mean umbilical vein and artery plasma cortisol concentrations compared within or between extradural or general anaesthesia groups. Extradural anaesthesia, in contrast to general anaesthesia, decreases the adrenocortical response to Cacsarean section surgery by blocking afferent neurogenic pathways from the surgical site. The method of anaesthesia does not influence the fetal cortisol response.