Introduction: As an alternative to general anesthesia, for upper limb surgeries, brachial plexus block is a popular approach. This type of block avoids the untoward effects of general anesthesia including upper airway instrumentation and thus prevents the consequences as shown by the available literatures. Aim: To compare 0.5% bupivacaine with normal saline and 0.5% bupivacaine with Dexamethasone (8 mg) in brachial plexus block by supraclavicular approach. Materials and Methods: This study was a single blinded, randomized study which was taken up among 70 patients aged between 18 to 65 years of ASA I and II posted for upper limbs. They were randomly divided into two equal groups where first group received 28 ml of Bupivacaine + 2 ml NS and second group received 28 ml of Bupivacaine + 2 ml Dexamethasone (8 mg) by supra clavicular approach. Results: Between the mean ages of two groups, there was no statistically significant difference. In Bupivacaine group, the mean time for onset of sensory block was 17.4 (± 3.5) min and in Bupivacaine dexamethasone group was 11.8 (± 2.7) min (p < 0.05). The mean time for onset of motor block in Bupivacaine group was 8.5 (± 4.4) min and in Bupivacaine dexamethasone group was 6.4 (± 1.8) min (p < 0.05). Both the differences were statistically significant (p < 0.05). The mean duration of sensory block in Bupivacaine group was 2.03 (± 1.4) hours and in Bupivacaine dexamethasone group was 5.85 (± 0.84) hours (p < 0.05). The mean duration of motor block in Bupivacaine group was 2.48 (± 0.59) hours and in Bupivacaine dexamethasone group was 6.97 (± 0.47) hours (p < 0.05). In Bupivacaine dexamethasone group patients required only 1 rescue analgesic dose. Rescue analgesic requirement in Bupivacaine group was higher (p < 0.05). No significant difference in hemodynamic variables i.e., pulse rate, systolic BP, diastolic BP and O2 saturation. Conclusion: In brachial plexus block, addition of dexamethasone to bupivacaine produced faster and longer duration of block and less number of rescue analgesics in post-op 24 hours.