Introduction: Addition of adjuvant to local anesthetic in supraclavicular brachial plexus block helps in rapid onset, increased duration of block and improved quality of analgesia. We compare clonidine and dexmedetomidine as an adjuvant to bupivacaine in supraclavicular brachial plexus block. Methods: Sixty ASA Grade I/II patients undergoing upper limb surgery under supraclavicular brachial plexus block. Two groups of 30 patients each and randomly assigned using computer generated random numbers. The patients were compared for onset as well as duration of sensory and motor blockade, duration of analgesia and hemodynamic side effects. Group C: Bupivacaine 0.25% (35 cc) + clonidine 1 μg/kg; Group D: Bupivacaine 0.25% (35 cc) + dexmedetomidine 1 μg/kg. Results: The onset of sensory block was shorter in dexmedetomidine group (statistically highly significant) as additive to bupivacaine compared to clonidine. Although no significant difference was seen in onset of motor block, the duration of sensory block and motor block was significantly prolonged in the dexmedetomidine group than in clonidine group. There was significant less rescue analgesia demanded by patients of dexmedetomidine group with no significant difference in block quality in both the groups. Conclusion: From the present study, it can be concluded that, dexmedetomidine prolongs the duration of sensory and motor block and enhances the quality of block as compared with clonidine when used as an adjuvant to in supraclavicular brachial plexus block.