Background/aim: This study compared ultrasound guided costoclavicular (CC) and lateral sagittal infraclavicular (LS) brachial plexus block in patients undergoing upper extremity surgery. Materials and methods: A total of 80 patients undergoing upper extremity surgery were randomly classified into two groups: Group CC (costoclavicular (n = 40)) and Group LS (lateral sagittal infraclavicular (n = 40)). Both groups received a 25 mL containing a mixture of 1% lidocaine and 0.25% bupivacaine. A blinded observer recorded the block onset time and decided which patients who were admitted to the operation room needed general anesthesia or rescue block or without any iv. narcotics for the surgical procedure. Results: The sensorimotor onset time was found to be faster in the CC group [(15.95 2.97) min] compared to the LS group [(17.72 4.15) min]. There was a statistically significant difference between two groups in terms of sensorimotor onset time (p = 0.031). There was no difference between two groups in terms of the block performance times and post-block motor block dissolution times. Conclusion: The CC approach provides faster onset of sensorimotor blockade than LS approach when the 4 major terminal nerves of the brachial plexus were evaluated.Key words: Costoclavicular approach, brachial plexus, infraclavicular block, sensorimotor blockade, upper extremity surgery