Objective:To evaluate the effect and safety of low-dose naloxone combined with sufentanil and ropivacaine for postoperative patient-controlled epidural analgesia (PCEA) in elderly patients undergoing total hip replacement. Methods: A total of 60 elderly patients (ASAⅠ-Ⅱ) undergoing total hip replacement were randomly assigned to two equal groups: Group C was given 0.5 μg/ml sufentanil in 0.15% ropivacaine; Group N was given the same solution with 0.09 μg/(kg·ml) naloxone. The 2 groups were followed up in a double-blinded manner: the visual analogue scale (VAS) for pain score was recorded at 2, 6, 12, and 24 h to evaluate the analgesia effect. Meanwhile, the incidences of postoperative nausea and vomiting (PONV), pruritus, sedation, respiratory depression, and hypotension were also recorded.Results: The VAS pain score in Group N was significantly lower than that in Group C at 6, 12 and 24 h (P<0.01). The incidence of PONV in Group N was significantly lower than that in Group C (P<0.05); the incidences of other opioid-induced side-effects were not significantly different between the 2 groups. During the course of analgesia, the vital signs of 2 groups were stable; no patients had respiratory depression or hypotension.Conclusion: Low-dose epidural naloxone can enhance the analgesic effect of sufentanil. With timely postoperative monitoring, low-dose naloxone combined with sufentanil and ropivacaine is safe and effective for postoperative patient-controlled epidural analgesia in elderly patients undergoing total hip replacement.