BACKGROUND: The purpose of this study was to find additional effects of intrathecal nalbuphine 1 mg to morphine 0.1 mg for pain relief during a cesarean section. METHODS: Sixty healthy patients at full term who were scheduled for an elective cesarean delivery with spinal anesthesia were enrolled in the study. They received 0.5% bupivacaine 10 mg with either morphine 0.1 mg (group M), or nalbuphine 1 mg (group N), or morphine 0.1 mg nalbuphine 1 mg (group M + N). Analgesic effects were evaluated by a verbal rating scale on the duration of complete analgesia (time from the intrathecal injection to the first pain report), effective analgesia (time from the intrathecal injection to the first analgesic request), and cumulative doses of additional analgesics. Hemodynamic changes and adverse effects were also observed. RESULTS: The duration of complete analgesia increased significantly in group M, compared with group N and group M + N. Effective analgesia was longer in group M and group M + N, compared with group N. The incidence of pruritus was significantly lower in group N, compared with group M and M + N. The incidence of nausea and vomiting was the same among all groups. CONCLUSIONS: We concluded that intrathecal addition of nalbuphine 1mg to morphine 0.1 mg during spinal anesthesia for a cesarean delivery reinforced intraoperaitive analgesia compared with intrathecal morphine 0.1 mg. However, it reduced the duration of complete analgesia and had no effect on the incidence of pruritus.