Background: Supraclavicular brachial plexus block is a popular technique of anaesthesia for surgeries on upper limb. It is safe and effective & offers analgesia postoperatively. Certain group of drugs may be used as adjuvants to local anaesthetics to decrease the local anaesthetics doses and enhances the efficacy of analgesia while reducing the incidence of adverse reactions. This study was conducted to assess the effect of addition of Dexmedetomidine to a mixture of local anaesthetics for brachial plexus blockade in adult patients posted for elective upper limb orthopedic surgeries. Objective: To study the effect of addition of 50µg of Inj. Dexmedetomidine as an adjuvant to a mixture of 2% Lidocaine with adrenaline (1:200000) 15 ml + 0.5% Bupivacaine 15ml on time of onset, time for maximum effect, duration of sensory and motor blockade, duration of postoperative analgesia and to note perioperative haemodynamics and sedation scores. Methods: 60 patients of either gender in the age group of 20–60 years posted for elective upper limb surgeries were selected for the study. Patients were randomly divided into two groups (n = 30). Control Group C (n=30) received Inj. Lidocaine with adrenaline (1:2, 00,000) 2% = 15ml + Inj. Bupivacaine (0.5%) = 15ml + Inj. Sterile water = 5ml. Total volume = 35ml. The study GroupD (n=30) received Inj. Lidocaine with adrenaline (1:2, 00,000) 15ml+ Inj. Bupivacaine (0.5%) = 15ml + Inj. Dexmedetomidine 50µg (0.5 ml diluted to 5 ml sterile water= 5ml). Total volume = 35ml. They were compared for onset and duration of motor and sensory block and the duration of postoperative analgesia. Results: Onset of sensory block: Group D: 1.73 ± 0.9min vs Group C: 6.0 ± 1.8min (p<0.001). Onset of motor block: Group D: 2.8 ± 1.0min vs Group C: 8.5 ± 2.4 min (p<0.001). Duration of sensory block: Group D: 622 ± 166.4min vs Group C: 240.6 ± 63.02min (p<0.001). Duration of motor effect: Group D: 450 ± 136.2min vs group C (191.3 ± 48.9) min (p<0.001). Duration of analgesia: Group D: 1163.3 ± 334.6 min vs Group C: 351.3 ± 83.9min (p<0.001). Conclusion: As an adjuvant Inj. Dexmedetomidine, when added to local anaesthetics a) Shortens the time of onset of block, b) Prolongs the duration of sensory and motor block, c) Prolongs the duration of postoperative analgesia with better hemodynamic stability both intra operatively and post operatively.