To evaluate the effect of the combination of bupivacaine with either nalbuphine or fentanyl to prolong the analgesic duration and to compare which of them is more effective with no need for supplementary analgesia. This study enrolled sixty children aged 1-6 years with American Society of Anesthesiologists (ASA) I or II, scheduled for elective lower abdominal surgeries receiving caudal block. Injection of bupivacaine 0.25% with addition of fentanyl (1 μ/kg) and nalbuphine (0.2 mg/kg). Pain assessment was the primary outcome, and secondary outcome included the first request of analgesia, the total dose of analgesic consumption, any complication and patient satisfaction. This study enrolled sixty children aged 1-6 years with the American Society of Anesthesiologists (ASA) I or II, scheduled for elective lower abdominal surgeries receiving caudal block. Divided into three groups: Injection of bupivacaine 0.25% in group (C), addition of fentanyl (1 μ/kg) with bupivacaine 0.25% in a group (F)and nalbuphine (0.2 mg/kg) with bupivacaine 0.25% (N). Hemodynamics were monitored, Pain severity was assessed perioperatively, postoperative analgesia requirement and side effects. In this study, the caudal block with Nalbuphine is more effective than Fentanyl in caudal block for lower abdominal pediatric surgeries.