62 patients scheduled for arthroscopic shoulder surgery were randomized to receive an ultrasound guided supra-clavicular brachial plexus block (SCBB) or an interscalene brachial plexus block (ISBB) for pain relief following surgery. The primary outcome of interest was pain intensity within the first 24 hours post-operation, measured on a Visual Analog Scale (VAS). Secondary outcomes included the proportion of patients requiring additional analgesics, time to first analgesic requirement, nerve blockade characteristics (scanning time, needling time, procedural time, onset time of sensory block, block failure) and adverse events. Results from the study revealed no significant differences between groups in VAS pain scores up to 12 hours. However at 24 hours, VAS pain score was significantly higher in the ISBB group. Additionally, the proportion of patients with Horner's syndrome was significantly higher in the ISBB group. There were no significant differences between the two groups in all remaining outcomes.