Abstract : Ultrasound-guided supraclavicular brachial plexus block reduces the probability of major complications occurrence. Adjuvants are added to local anesthetics to improve various block characteristics. Clinical and preclinical data demonstrate the analgesic actions of adenosine. The present study aims to compare the analgesic efficacy and safety of ultrasound guided continuous supraclavicular brachial plexus block using levobupivacaine alone and that of levobupivacaine combined with adenosine for anesthesia and pain control in upper limb cancer surgery. Outcome parameters included success rate, time of onset of the sensory block, motor block, visual analogue scale (VAS) for pain, at 30 min, 2 h, 12 h, 24 h, 36 h, and 48 h postoperatively, time to first rescue analgesia and analgesia related complications. The study included 120 adult ASA I-II patients scheduled for different upper limb cancer surgeries. A bolus dose is 40 ml of 0.25% of levobupivacaine alone in LB group or 40 ml of 0.25% levobupivacaine + 12 mg adenosine in LBA group. We noted significantly shorter time to sensory block in the LBA group. However, no significantly differences were noted between the studied groups regarding motor block score. Also, there were significantly lower VAS values in LBA group throughout the study assessment intervals. Moreover, there was significantly shorter time to rescue anesthesia in LB group. Both groups had equal success rates (98.3 %) with no side effects. In conclusion, adding adenosine to levobupivacaine during ultrasound-guided supraclavicular brachial plexus block has many advantages but it doesn’t affect the analgesic success rate