['To examine the analgesic effect of preoperative administration of flurbiprofen axetil and that of postoperative administration of a combination of flurbiprofen axetil and fentanyl, as well as perioperative plasma β-endorphin (β-EP) levels in patients undergoing esophagectomy.', 'Forty-five patients were randomly divided into three groups: group A: 100\xa0mg flurbiprofen axetil preoperative, 10\xa0μg/kg fentanyl\xa0+\xa010\xa0ml placebo postoperative; group B: 100\xa0mg flurbiprofen axetil preoperative, 10\xa0μg/kg fentanyl\xa0+\xa0100\xa0mg flurbiprofen axetil postoperative; group C: 10\xa0ml placebo preoperative, 10\xa0μg/kg fentanyl\xa0+\xa010\xa0ml placebo postoperative. Postoperative analgesia was achieved by intravenous infusion containing flurbiprofen axetil and/or fentanyl at 2.0\xa0ml/h (total volume, 100\xa0ml) using infusion pumps. The β-EP was measured at preanesthesia (T(1)), the end of surgery (T(2)), 24\xa0h (T(3)), and 48\xa0h (T(4)) after surgery. Visual analog scale scores (VAS) at T3, T4 (at rest), and rescue analgesic tramadol requirement was recorded.', 'The VAS of group B was significantly lower than group A and C (P\xa0<\xa00.01) at T(3) and T(4). The β-EP levels at T(2)-T(4) in group A did not differ significantly from those at T(1) (P\xa0>\xa00.05); however, the β-EP levels in group B at T(3)-T(4) increased significantly (P\xa0<\xa00.05), while those in group C increased at T(2) and decreased at T(4) (P\xa0<\xa00.05). The β-EP levels in group B at T(3) and T(4) were the highest as compared to its levels in groups A and C (P\xa0<\xa00.01). Tramadol consumption in group B was significantly lower than in groups A and C (P\xa0<\xa00.01).'] Does flurbiprofen axetil enhance analgesic effect of fentanyl associated with increase in β-endorphin levels?