Role of Peripheral Nerve Block has expanded from operating suite into the arena of postoperative and chronic pain management. Single shot Brachial Plexus Block can provide analgesia only for period of action of local anaesthetic used. Keeping this in mind various drugs have been used as adjuvants to local anaesthetics with a view to increase analgesic efficacy and for extending duration of analgesia . The present study was undertaken to compare efficacy of adjuvant fentanyl and clonidine to local anaesthetics in Supraclavicular Brachial Plexus Block using nerve stimulator. Seventy patients aged 18 to 60 years scheduled for upper limb surgery in Poona Hospital & Research Centre, Pune between May 2014 and May 2015 under Supraclavicular Brachial Plexus Block and ready to participate were included. They were randomly divided into two equal groups of 35 each. Group C received 25ml 0.5% Bupivacaine + 1 µg /kg body wt of Clonidine whereas Group F received 25ml 0.5% Bupivacaine + 1 µg /kg body wt of Fentanyl. Mean onset of sensory and motor block , mean complete onset of sensory and motor block was significantly higher in Group F as compared to Group C. Mean duration of analgesia was significantly less in Group F as compared to Group C. Addition of Fentanyl and Clonidine to local anaesthetic mixture did not cause any significant cardiovascular or respiratory disturbances and incidence of complications and side effects were minimal. Clonidine was better adjuvant to local anaesthetics in Supraclavicular Brachial Plexus Block.