Background:The shorter duration of action of typical local anaesthetics used for spinal anaesthesia demands the early need for postoperative analgesia. Epidural analgesic administration reduces the stress reaction to pain and surgery, reduces the requirement for systemic analgesics, and promotes early rehab.1 It was discovered that using opioids as an adjuvant to local anaesthetics has synergistic effects. The advantages of this combination were improved pain alleviation, motor sparing, and less toxicity.2 Objective:To compare the efficacy of epidural analgesia by using fentanyl and nalbuphine as adjuvants along with bupivacaine following lower limb surgeries with respect to Onset, Duration, and side effects. Meterials and Methods:Prospective randomized doubled blind comparative study would be conducted on 60 adult patients of ASA grade I & II in the age group of 18 to 59 years of either sex, posted for lower limb surgeries after taking informed written consent. Patients were randomly divided on an alternative basis into 2 groups of 30 each. In study conducted in AL-AMEEN MEDICAL COLLEGE. VIJAYAPUR, KARNATAKA during the period of April 2021 to December 2022. If visual analogue score is more than one ,GROUP A: Patient received 50ug of fentanyl + 2.5 ml 0.5% bupivacaine diluted to 10ml with distilled water given epidurally (0.125%). GROUP B: Patient received 5mg of nalbuphine +2.5 ml 0.5% bupivacaine diluted to 10ml with distilled water given epidurally (0.125%). . Noting onset and duration analgesia also monitoring of patients SBP,DBP,SpO2,RR,VAS score till 15 min followed by 30 min,1hr ,2hr,4hr ,6hr,8hr is done and asked for any side effects like nausea ,vomiting, pruritis ,sedation and urinary retention. Conclusion: Epidural fentanyl has faster onset of action compared to nalbuphine and has longer duration of action compared to nalbuphine , for post operative epidural analgesia. There was no any statistically significant side effects in any of the two groups.