Introduction: In the present-day practice of Anaesthesiology Bupivacaine is the most commonly used drug for subarachnoid block. Many adjuvants have been tried to improve the quality of analgesia and to prolong the duration of action. The present study was conducted to assess the efficacy between dexmedetomedine versus Fentanyl as an adjuvant to Bupivacaine in lower abdominal and lower limb surgeries. Methods: 60 patients of ASA gr I and II aged between 18-60 years undergoing elective lower abdominal, urologic, lower limb surgeries were selected and divided into two groups of 30 each. Group “BP” received intrathecally 12.5mg 0.5% of Bupivacaine + 5 µg of dexmeditomedine while group “BF” received 0.5% Bupivacaine +12.5µg of Fentanyl. Onset of sensory and motor block, highest level of sensory blockade, duration of analgesia was assessed. Result: The onset of Sensory and motor blockade was same in both the groups. Duration of sensory block and analgesia was significantly prolonged in Dexmeditomedine group. So also, was the duration of motor block. Conclusion: Dexmeditomedine potentiates Bupivacaine spinal anaesthesia more than Fentanyl.