Abstract:Aim: To study the clinical effects and aversive side effects of different dosage of droperidol on the post operative patient control epidural analgesia (PCEA) with tramadol. Methods: 320 patients scheduled for postoperative PCEA were randomly and evenly divided into four groups of 80 each. Group A: 1% tramadol 0.15% bupivacaine(control group); group B: 1% tramadol 0.15% bupivacaine 0.005% droperidol; group C: 1% tramadol 0.15% bupivacaine 0.010% droperidol; group D: 1% Tramadol 0.15% bupivacaine 0.015% droperiol. All patients were taken PCEA for 24 hours with Graseby 9300 microcomputer infusion PCA pump. Results: The analgesic effects of group B, C and D were satisfactory and better than that of group A ( P <0.05).The occurrence of nausea and vomitting was decreased ( P <0.01) and the somnolence rate were increased along with the increase of the droperidol concentration. Conclusion: Moderate dosage of droperidol (0.01%) is beneficial for post operative pain control using PCEA with tramadol and is effective in decreasing the occurrence of aversive side effects such as nausea and vomitting.