Postoperative analgesia using continuous epidural morphine or a single intrathecal injection of morphine has been compared with standard patient-controlled analgesia (PCA) in lumbar fusion patients. Pain relief with epidural morphine was dramatic in some cases (3/12) but was not predictable, and catheter displacement was a frequent occurrence. A single intrathecal bolus of morphine had no advantage over PCA alone. Complications of both intraspinal techniques included nausea and pruritis. No respiratory depression was observed.