Caudal block is the regional anesthetic technique that is used most frequently in pediatric surgery. Opioid drugs have been added to local anesthetic solutions to prolong duration of analgesia but ideal combination were not found that has minimal adverse effect. The aim of this study was to compare the postoperative analgesic efficacy of equal concentrations of bupivacaine plus tramadol or levobupivacaine plus tramadol in pediatric patients undergoing minor urological surgery.