INTRODUCTION– The use of peripheral nerve blocks for anaesthesia and post–operative analgesia has increased significantly recent years. Various adjuvants (Opioids, α–2 Agonist, Magnesium, Neostigmine) frequently added to local anaesthetics to prolong analgesia following peripheral nerve blockade. Due to adverse effects of these adjuvants, we have conducted our study on Dexamethasone. Our study aimed to find out analgesic efficacy of different doses of Dexamethasone as adjuvant to Levobupivacaine .MATERIAL & METHODS– PNS guided brachial plexus block was given to sixty patients, randomly assigned into two groups.Group–D4: received 4mg of Dexamethasone ( diluted to 2ml) with 23ml of 0.5% Levobupivacaine.Group–D8: received 8mg of Dexamethasone (2ml) with 23ml of 0.5% Levobupivacaine.Onset & duration of sensory & motor blockade, time for first rescue analgesia and complications are assessed during intra–operative & post–operative period. RESULTS– The onset of sensory & motor block was faster in Group–D8 when compared to Group–D4. Time for request for first rescue analgesia appeared earlier in Group–D4 when compared to Group–D8.CONCLUSION– Addition of 8mg Dexamethasone to Levobupivacaine in supraclavicular brachial plexus blockade had earlier onset of sensory & motor block, prolonged the duration and time for first rescue analgesia.