Background: Lumbar epidural anesthesia is widely used regional blockade method. But postepidural back pain is most common cause that experienced patients refuse epidural anesthesia. We planned this study to evaluate the effect of epidural dexamethasone injection for postepidural back pain. Methods: Adult patients free of back pain were randomly allocated into two groups. In both group anesthesia was induced with 2% lidocaine 20~25 ml mixed with 1:200,00 epinephrine and fentanyl 0.1 mg. After surgery, epidural catheter was removed after epidural dexamethasone injection in one group (group 2). In other group (group 1), catheter was removed without treatment. We visited patients and asked existence of back pain, and the intensity of back pain was measured by visual analogue scale at 24, 48 and 72 hours after surgery. Statistical analysis was done by Student's t-test and Mann-Whitney test. Results: In group 2, there was significant decrease in number of patients suffering from back pain and intensity of back pain. Conclusion: Epidural dexamethasone injection results in decreased number of patients suffering from back pain and also less in intensity of back pain.