Background:Supraclavicular brachial plexus block is a popular and widely employed regional nerve block technique for perioperative anesthesia and analgesia for surgery of the upper extremity. Coadminstration of local anaesthetics and several adjuvants is now a good way to hasten the onset of the block and to increase its duration.aim of study was to evaluate the effects of dexamethasone and magnesium sulfate as additives to bupivacaine in supraclavicular brachial plexus block.Patients and Methods:A Prospective randomized controlled comparative clinical study was conducted on 36 healthy patients of ASA grade I, II of age group 21-60 years scheduled for upper limb surgeries under supraclavicular brachial plexus block.Patients were allocated to three groups of 12 each as a control group(C)received 20ml 0.5%bupivacaine,group(D) received 18 ml bupivacaine 0.5% + 2 ml(8mg)dexamethasone,group(M) received18ml bupivacaine0.5% + 2ml(200 mg)magnesium sulfate.Parameters observed were onset and duration of sensory and motor blocks and Timing and total amount of rescue analgesia.hemodynamics and complications were also recorded.Results:Dgroup significantly shorter regard onset of sensory and motor blocks followed byM group then Control Group.Also,D group significantly longer regard duration of sensory and motor blocks and time of first analgesia followed by M group then Control Group.Total rescue analgesia and Number of Rescue Analgesia were significantly lower in groupD followed by Mgroup then Control Group.Conclusion:Addition of Dexamethasone or Magnesium sulphate to Bupivacaine0.5% for supraclavicular brachial plexus block fastened the onset of sensory and motor blocks and prolonged the duration of sensory and motor blocks, with Dexamethasone showed better results.