Background: Ultrasound guided (USG) supraclavicular brachial plexus (SPB) block can be performed either by a single injection (SI) technique, injecting the entire volume of drug in the corner pocket or by a double injection (DI) technique, whereby half the volume of the drug is injected in the corner pocket and remaining half directly into the neural cluster. We conducted this study to compare thesuccess rates of the two techniques. Methods: A comparative two group study was carried out in 120 patients who underwent elective upper limbsurgeries (excluding the shoulder) under USG guided SPB in M.S. Ramaiah Hospital, Bangalore. Patients were randomly allocated in two groups (SI & DI). Both the groups received 30 ml 0.5% ropivacaine. SI group received the entire volume in the corner pocket, whereas DIgroup received 15 ml in corner pocket and the remaining 15 ml in the neural cluster. The blocks were assessed every 5 mins upto 30 mins forboth sensory and motor blockade using cold test and motor movements respectively, in the musculocutaneous, median, radial and ulnar nerves distribution. Each nerve was allocated a maximum of 2 points for complete blockade. Hence a maximum composite score of 16 could be achieved. To label a block successful a minimum of 14 points were required. We compared the success rate of blockade and total anaesthesia related time between the two groups. Results: The success rate of the blockade in the SI and DI group was 96.7% and 91.7% respectively at 30 min of performing the block which was not statistically significant. All the seven patients who had failure in both the groups had ulnar nerve sparing. The mean total anaesthesia related times in the two groups were 21.42±3.29 and25.17±2.45 in DI and SI groups respectively with P<0.001. During the first 25 minutes, the DI group displayed a higher proportion of patients with minimal composite score of 14 points. Fifty eight patients(96.7%) in DI achieved a composite score of 14 points and above within the first 25 minutes. The mean onset times were 17.25±2.83 and 22.72±2.47 in DI and SI group respectively. No adverse events were seen in both the groups. Conclusions: The success rates in both the SI and DI techniques were comparable. The DI technique results in a faster onset and hence a shorter total anaesthesia related time, which however may not be clinically relevant.