Background: Initially the concept of pain was emotional rather than a sensory modality. The word pain is acquired from the Greek word poine which means “penalty”.1 The International Association for the Study of Pain (IASP) described pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage”.2 Peripheral nerve blocks have become a popular anaesthetic option in the perioperative management of patients because nerve blocks provide better postoperative analgesia than does general anaesthesia, while avoiding the cardiopulmonary and central nervous system effects of general anaesthesia. Peripheral nerve block is a technique which uses local anaesthetic to be deposited around a target nerve and block the conduction of action potential thus not allowing pain signals to be transmitted to the pain centre in the brain. Materials & methods: A prospective randomised single blinded study was conducted at Vinayaka Missions Kirupananda Variyar Medical College & Hospitals, Salem from December 2019 to May 2021. A total of 60 Adult patients of both gender undergoing upper limb elective surgeries under brachial plexus block were allocated in two groups I & II and each group comprises 30 patients were selected for the purpose of the study. Results: The association of age group between both the groups was found to be statistically insignificant with mean age of 43.1+12.4 years of age in Group 1 and 43.3+11.9 years of age in Group 2. The mean time of onset of sensory block in group I was 16.47 mins & in Group II was 10.57 mins. This was found to be clinically highly significant with P < 0.0001. The duration of Sensory Block between both the study and control group was found to be statistically insignificant whereas the duration of Motor blockade was found to be statistically significant along with the no of RA given in 24 hours which was also found to be statistically significant. The difference of pulse rate between both the groups at various intervals was found to be statistically insignificant. The Oxygen saturation between both the group was found to be statistically insignificant till 60 minutes of the procedure and it was found to be statistically significant after 2 hours till the end of the study. Conclusion: We conclude that adding dexamethasone to the local anaesthetic provides rapid onset of both sensory and motor blockade, and prolongs the motor blockade and analgesia duration.