We have examined the effect of intraoperative and postoperative (4 h) continuous spinal anaesthesia for colonic surgery on the postoperative glucose, lactate and cortisol responses. Twenty-one patients were studied; the first group (control) received general anaesthesia, the second group (extradural) an extradural block (T4-S5) and the third group (spinal) a continuous spinal block (T4-S5). Plasma concentration of glucose increased significantly in the control and extradural groups (P less than 0.05) after surgery, with a small change in the spinal group. Plasma concentration of lactate increased significantly (P less than 0.05) in the control group only. The postoperative increase in plasma concentration of cortisol was similar in both control and extradural groups, and significantly greater than that of the spinal group (P less than 0.05). Thus continuous spinal analgesia attenuated, but did not abolish, the increase in plasma concentration of cortisol associated with colonic surgery.