Aims and objectives: The aim of this study was designed to compare clonidine and dexmedetomidine, used as an adjunct to bupivacaine in supraclavicular brachial plexus block in terms of efficacy in onset, duration and potency of sensory and motor block, sedation score and analgesia. Study design: In this prospective, double blind randomized controlled clinical trial, 60 American Society of Anaesthesiologists grade 1 and 2 (ASA 1, 2) patients aged between 18 to 60 years, scheduled for upper limb surgeries under supraclavicular block were selected. Materials and methods: The patients were divided into two groups: Group C (n= 30) comprised of patients who received bupivacaine 0.25% (35 cc) + injection clonidine 1 mcg / kg and Group D (n= 30) who received bupivacaine 0.25% (35 cc) + inj dexmedetomidine 1 mcg / kg. Onset, duration of sensory and motor blockade, duration, efficacy and potency of postoperative analgesia, sedation score and any untoward side effects, if any were observed at scheduled intervals. Statistics and Results: The mean time for onset of sensory block in group D was (9.17±1.26) mins and that observed in group C was (11.07±2.14) mins. This difference was statistically significant (p = 0.001). Time to achieve complete sensory block in group D was (14.80 ± 1.37) mins and in group C was (16.40±2.09) mins. This difference was statistically insignificant (p > 0.005). Mean duration of sensory block in group D was (690 ± 87.41) mins and in group C was (470 ± 55) mins This difference was statistically significant (p<0.05) (p = 0.001) The duration of analgesia was (721.33 ± 88.27) mins in group D and (516.00±45.15) mins in group C (p< 0.05) This difference was statistically as well as clinically significant. No patient in any group required intra-operative supplementation with analgesia or general anaesthesia during the surgical procedure. Conclusion: From our results we conclude that the onset of sensory and motor block is faster with dexmed