Background: Postoperative pain can have immediate and long-term consequences, including poor outcomes and prolonged hospitalization. It can also lead to chronic pain if not treated. Wound site infiltration with local anesthetic agents provides desirable analgesia for postoperative pain relief. The purpose of this study was to compare the analgesic effectiveness of local wound infiltration with a mixture of bupivacaine and tramadol (BT) versus bupivacaine alone (BA) for postoperative analgesia. Method: A prospective cohort study design was employed on 120 patients who underwent elective lower abdominal surgery under general or spinal anesthesia and were selected by using a systematic random sampling technique. Patients were divided into two groups based on the anesthetist in charge of postoperative pain management. Patients who received BT at the end of surgery are called BT groups, and patients who received BA are called BA groups (control). Result: The median (interquartile range) of pain severity score was significantly lower in the BT group as compared to the BA group with a p-value of 0.001. And, the median time to first analgesic request in the BT group was significantly longer as compared to patients in the BA group, with a p-value of 0.001. Conclusion: Local wound infiltration with BT decreases the postoperative pain score, total analgesic consumption, and has a prolonged time to first analgesia request as compared to BA. Therefore, we recommend using a local wound infiltration with BT to be effective for postoperative analgesia in patients undergoing elective lower abdominal surgery under general or spinal anesthesia. Highlights