In a controlled study a single segment combined spinal epidural (CSE) block was compared with spinal or epidural block for major orthopaedic surgery. Seventy-five patients, age 52-86 yr, were randomly assigned to receive one of the three blocks. Bupivacaine 0.5% was used for surgical analgesia. The postoperative pain relief after 4.0 mg epidural morphine was compared with the analgesic effect of 0.2 or 0.4 mg morphine administered intrathecally. With the spinal technique good or excellent surgical analgesia and muscle relaxation were achieved rapidly (11.8 +/- 1.1 min). The time taken to provide an equally effective and reliable block with the CSE technique was no longer (14.9 +/- 2.2 min). For epidural block with the catheter technique more time was required (35.9 +/- 3.9 min) to provide acceptable surgical conditions (P < 0.05). Perioperative sedatives and concomitant analgesics were required more frequently and in larger doses by the patients undergoing surgery with epidural block (P < 0.05) than with CSE or spinal block. Our study demonstrated that the analgesia after surgery provided by 0.2 and 0.4 mg morphine administered intrathecally was comparable to that provided by 4.0 mg of epidural morphine. It is concluded that the analgesia and surgical conditions provided by the spinal and CSE blocks were similar and were superior to those provided by an epidural block.