Background One of the main objectives of anesthesia is to relieve the patient’s pain and agony, by ensuring the performance of surgical procedures without any discomfort. Elimination of postoperative pain is indispensable due to the central, peripheral and immunological stress response to tissue injury. So there is a need for extended analgesia without any side effects to achieve this goal. Aim of the Work To compare the post-operative analgesic effect of intrathecal-nalbuphine and fentanyl as adjuvant to bupivacaine during cesarean delivery. The secondary aim is to compare side effects between using nalbuphine and fentanyl as adjuvants to bupivacaine. Patients and Methods After Approval is obtained from the research Medical Ethical Committee of Faculty of Medicine, Ain Shams University. The study was conducted on 60 patients that were randomly selected. Randomly divided into 2 groups 30 patients each. Group F which received fentanyl as adjuvant while group N received nalbuphine as adjuvant. Results The addition of a small dose of nalbuphine or fentanyl to bupivacaine in spinal anesthesia prolonged the time of postoperative analgesia. In this study, there was no significant difference regarding the age, height, weight, and duration of operation, maximum sensory level, and maximum motor blockade level. The duration of the postoperative analgesia was prolonged with Nalbuphine group in comparison to the fentanyl group, the results were highly significant. Conclusion We concluded that either intrathecal nalbuphine (0.8 mg) or intrathecal fentanyl (25 µg) combined with Bupivacaine improves intraoperative analgesia and prolongs early post-operative analgesia in cesarean section. There was no significant difference with regard to: Peak sensory block level, Maximum motor block level, systolic blood pressure, diastolic blood pressure, oxygen saturation, and heart rate.