Background: Continuous epidural block is widely used for surgical operation and postoperative pain management. The potential infection due to the epidural catheter is a definite harzard of continous epidural block. We investigated the effectiveness of bacterial filter in prevention of infection due to the epidural catheter. Methods: Patients scheduled for transabdominal hysterectomy were assigned to two groups by simple randomization (50 patients per group). All catheters were placed in the 2nd and 3rd lumbar epidural space, using careful sterile technique. Group 1 received injections by the epidural catheter with a bacterial filter and group 2 received injections by the epidural catheter without a bacterial filter. The infection rate in the tips of epidural catheter left for 3 days were compared between the two groups. Results: There was no significant difference in the infection rate between two groups. Conclusions: A bacterial filter of the epidural catheter for surgical anesthesia and postoperative analgesia dose not prevent all kinds of infection in continuous epidural block.