In this prospective study we compared ultrasound-guided (USG) infraclavicular and supraclavicular blocks for performance time and quality of block. We hypothesized that the infraclavicular approach would result in shorter performance times with a quality of block similar to that of the supraclavicular approach. Eighty patients were randomized into two equal groups: Group I (infraclavicular) and Group S (supraclavicular). All blocks were performed using ultrasound visualization with a 7.5-MHz linear probe and neurostimulation. The anesthetic mixture consisted of 0.5 mL/kg of bupivacaine 0.5% and lidocaine hydrocarbonate 2% (1:3 vol.) with epinephrine 1:200,000. Sensory block, motor block, and supplementation rates were evaluated for the musculocutaneous, median, radial, and ulnar nerves. Surgical anesthesia without supplementation was achieved in 80% of patients in group I compared with 87% in Group S (P = 0.39). Supplementation rates were significantly different only for the radial territory: 18% in Group I versus 0% in group S (P = 0.006). Block performance times were not different between groups (4.0 min in Group I versus 4.65 min in Group S; P = 0.43). Technique-related pain scores were not different between groups (I: 2.0; S: 2.0; P = 1.00). We conclude that USG infraclavicular block is at least as rapidly executed as USG supraclavicular block and produces a similar degree of surgical anesthesia without supplementation.