The results of postoperative epidural administration of saline solution (a placebo), morphine, methylprednisolone, and a combination of morphine and methylprednisolone for the reduction of pain after an operation for spinal stenosis or a herniated intervertebral disc were compared in a prospective, randomized blinded study. Epidural administration of morphine and methylprednisolone--either alone or in combination--significantly reduced the need for analgesia after an operation for spinal stenosis (p < 0.05) but not after an operation for a herniated intervertebral disc. Morphine and methylprednisolone did not have an addictive effect on the reduction of pain. Itching was significantly more common in the patients who had received morphine than in those who had received the placebo (p = 0.04). Although urinary retention was more frequent after the use of morphine than after the use of the placebo, the difference was not significant with the size of the sample that was analyzed (p = 0.25).