Epidural morphine with butorphanol for postoperative analgesia after cesarean delivery. Epidural morphine has been used more and more to provide long-lasting postoperative analgesia after cesarean delivery. However, the incidence of pruritus (20%-93%) and nausea (17%-60%) detract from the usefulness of epidural morphine. The purpose of this study was to evaluate, in 30 patients having epidural anesthesia for cesarean delivery, the analgesic efficacy and side effects when a combination of epidural morphine, a mu-receptor agonist, and butorphanol, a mu-receptor antagonist and kappa-receptor agonist, was administered. After clamping of the umbilical cord, patients received 4 mg epidural morphine with 3 mL of normal saline (group 1), 4 mg epidural morphine with 1 mg butorphanol and 2 mL of normal saline (group 2), or 4 mg epidural morphine with 3 mg butorphanol (group 3). Patients were monitored for 24 h after administration of the study medications. There were no significant differences between the groups in visual analogue pain scores, time to first analgesic request, respiratory rate, or Trieger dot test performance in the 24 h immediately after these epidural injections. There were three patients in group 1 and one patient in group 2 who experienced oxygen saturations less than 90%. (No patients in group 3 developed an oxygen saturation less than 92%.) The patients in group 3 did not require treatment for pruritus or nausea, a response significantly different (P less than 0.001 and P less than 0.05, respectively) from group 1 or group 2. 