Abstract: Objective To evaluate the effect of perioperative continuous epidural morphine administration on plasma D-dimer level in patients undergoing total hip replacement. Methods Forty ASA Ⅰ-Ⅱ patients undergoing total hip replacement under epidural anesthesia were randomized into two groups. In one group, the patients were given epidural administration of morphine 15 min before operation at 4 mg (in 10 ml normal saline) and for 48 h after the operation at 80 μg/h, while those in the other group received epidural injection of the same amount of normal saline before operation and 0.15% ropivacaine 2.0 ml/h for 48 h in the same manner after operation. Blood samples were taken before anesthesia (T0), at the end of operation (T1), and 24 h and 48 h after operation (T2 and T3) for determination of plasma IL-6 and D-dimer levels. Results In both groups plasma IL-6 and D-dimer levels showed significant increase at T1, T2 and T3 in comparison with those at T0, and their levels were significantly lower in morphine group than in ropivacaine group at T1, T2 and T3. Conclusion Epidural morphine can lower plasma IL-6 and D-dimer levels and correct blood hypercoagulability in patients undergoing total hip replacement.