Background and Aims: For early onset and prolonged postoperative analgesia various adjuvants are used with local anaesthetic agents in brachial plexus block. The aim of this study was to compare the effects of clonidine and dexmedetomidine as an adjuvant in brachial plexus blocks. Methods: In present study 25 cases were taken for each group. Group I (n=25) Control group = received 28 ml levobupivacaine 0.5%. Group II (n=25) received 28 ml levobupivacaine 0.5% plus 1 mcg/kg clonidine. Group III (n=25) received 28 ml levobupivacaine 0.5% plus 1 mcg/kg dexmedetomidine. local anaesthetic agents in brachial plexus block. The aim of this study was to compare the effects of clonidine and dexmedetomidine as an adjuvant in brachial plexus blocks. Methods: In present study 25 cases were taken for each group. Group I (n=25) Control group = received 28 ml levobupivacaine 0.5%. Group II (n=25) received 28 ml levobupivacaine 0.5% plus 1 mcg/kg clonidine. Group III (n=25) received 28 ml levobupivacaine 0.5% plus 1 mcg/kg dexmedetomidine. All the solutions were diluted with normal saline to make a total volume of 30 ml. The brachial plexus block with classical supraclavicular approach was given. Observations including hemodynamic variables (heart rate, blood pressure, respiratory rate and o2 saturation), onset and duration of sensory and motor block, duration of analgesia and degree of sedation were noted. Results: The difference in onset of sensory & motor block (early in dexmedetomidine group), duration of sensory & motor block and duration of analgesia (prolonged in dexmedetomidine group) was found to be statistically significant between all the groups (p<0.05). Effect on hemodynamic vitals was found significant between group I and group III & group II and III.  No significant difference between group I and group II is seen. There was no incidence of clinically significant hypotension, bradycardia in the perioperative period in any of group and no active intervention was required. The degree of sedation was slightly more in dexmedetomidine group. Conclusion: The supraclavicular brachial plexus block with dexmedetomidine adjuvant caused early onset of sensory and motor blockade and is highly effective in prolonging the duration of sensory and motor blockade and postoperative analgesia with better quality of block as compared to levobupivacaine alone or with clonidine as adjuvant.