Odjectives: With the utilizing of ultrasound, supraclavicular brachial plexus block using minimal effective volume of 20 ml. Moreover, the low dose anesthetic with low volume facilitates complications prevention but it is still sufficient effective local anesthesia. We aimed to determine the effect of ultrasound - guided supraclavicular brachial plexus block by 20 ml local anesthetic for one third lower arm - hand surgery. Methods: Fifty patients belonging to American Anesthesiology Society physical status Classes I, II, and III scheduling for elective one third lower arm - hand surgery were randomly divided into two groups. Group I received supraclavicular block with 20 ml levobupivacaine 0.375%. Group II received supraclavicular block with 20 ml of 1.5% lidocaine mixed with 1/200000 adrenaline. Results: The block was successful in 100%. The average time of sensory and motor inhibition of the levobupivacaine group of 8.43 ± 1.90 and 6.52 ± 1.85 hours was longer than that of the lidocaine group of 2.72 ± 0.99 and 2.26 ± 0.87 hours respectively with p < 0,05. The duration of analgesia of the levobupivacaine group (9.66 ± 1.84) hours was longer than that of the lidocaine group (4.19 ± 2.24) hours with p < 0,05. No complications have been encountered. Conclusion: With the utilizing of ultrasound, a minimal effective volume of 20 ml has been effected highly and decreased incidence of complications for supraclavicular brachial plexus block.