Background and Aim: Brachial plexus blocks provide excellent anaesthesia and post operative analgesia for upper limb surgeries. Various adjuvants like opioids, midazolam and 2 agonists have been used to improve the quality of block. Present study was undertaken to compare the onset and duration of Supraclavicular block between clonidine and dexmedetomidine when added as adjuvant to local anaesthetic. Methods: The study was conducted at Department of Anesthesia, Gujarat Adani Institute of Medical Science, Bhuj, Kutch, Gujarat. 50 patients undergoing forearm surgery under ultrasound guided supraclavicular block were randomized to receive 20ml of 0.25% bupivacaine with dexmedetomidine 1g/kg (Group BD) or 20ml of 0.25% bupivacaine with clonidine 1g/kg (Group BC). The onset and duration of sensory and motor block was assessed. The duration of post operative analgesia was also noted. Results: The mean time of onset of sensory and motor block was significantly faster in Group BD (8.8±0.91min, 11.3±0.952) than Group BC (11.14±1.13min, 13.6±1.11), respectively. The mean duration of sensory and motor block in group BD (9.3±0.667hrs, 8.5±0.692hrs) were found to be significantly longer than in group BC (7.06±0.664, 6.66±0.657). Conclusion: Dexmedetomidine produces faster sensory and motor block and prolongs the duration of analgesia as compared with clonidine when used as an adjuvant to Bupivacaine in supraclavicular block.