Background and Objectives: We evaluated the effect of adding dexamethasone to ropivacaine for supraclavicular brachial plexus blockade. The primary endpoints were the onset and total duration of sensory and motor block, quality of analgesia and duration of analgesia. Methods: Eighty patients of age group 20-50 years, scheduled for various elective orthopaedic surgeries on forearm and around the elbow under supraclavicular brachial block were divided into 2 equal groups in a randomized, double-blinded fashion. In group R (n=40), 30ml (150 mg) of 0.5% ropivacaine +2ml saline and in group RD (n=40), 30ml (150 mg) of 0.5% ropivacaine +2ml dexamethasone (8mg) were given. Motor and sensory block onset times, block durations, quality of intraoperative analgesia and duration of analgesia were recorded. Results: Demographic data and surgical characteristics were similar in both groups. The sensory and motor block onset time was earlier in group RD as compared to group R (P<0.05). Sensory and motor blockade duration were longer in group RD than in group R (P<0.001). Duration of analgesia was longer in group RD than in group R (P<0.001). The 24 hour Visual Analog Scale was more in group R as compared to group RD. The quality of anaesthesia was excellent in both the groups. Mean arterial blood pressure levels in groups at 5, 10, 15, 30, 45, 60, 90,120 and 150 minutes were statistically insignificant between the two groups (P>0.05). The mean pulse rate at different time intervals were statistically insignificant between the groups (P>0.05). Conclusions: Dexamethasone added to ropivacaine for supraclavicular brachial plexus block prolongs the duration of the block and the duration of postoperative analgesia.