['Because morphine affects various immune functions, patient-controlled analgesia with morphine may further deteriorate the immune mechanisms after surgery. Therefore, the purpose of this study was to determine differences between morphine patient-controlled analgesia and a combination of morphine and ketorolac in interleukin-6 and interleukin-10 responses, and in analgesia and morphine-related side effects.', 'Prospective study.', 'Twenty-two patients who underwent abdominal hysterectomy were classified randomly into two groups: (1) patient-controlled analgesia with morphine; and (2) patient-controlled analgesia with a combination of morphine and ketorolac. Blood samples to measure cytokines were collected at preoperatively, immediately postoperatively, and 2 hours, 4 hours, and 24 hours postoperatively.', 'Plasma was separated and frozen until the analysis of cytokines using enzyme-linked immunosorbent assays. Postoperative pain was assessed using a visual analog score. Sedation was checked based on a protocol developed at the Samsung Medical Center.', 'In the two groups, interleukin-6 increased immediately postoperatively, and it remained consistent for 24 hours. Interleukin-10 concentrations peaked at 2 hours postoperatively and progressively decreased. Cytokine concentrations between the two groups were significantly different for interleukin-6 24 hours postoperatively (p = 0.026) and for interleukin-10 4 hours postoperatively (p = 0.045). Total analgesic use was not different, but morphine consumption was significantly different (p = 0.037 at 4 hours postoperatively, p = 0.015 at 24 hours postoperatively). Pain scores, sedation, and side effects were unaffected by the patient-controlled analgesia regimen.'] Are plasma levels of interleukin-6 and interleukin-10 affected by ketorolac as an adjunct to patient-controlled morphine after abdominal hysterectomy?