Background: Supraclavicular brachial plexus block is one of the most effective anesthetic procedures in operations for the upper extremity. It has gained importance as regional anesthetic technique for surgical, diagnostic and therapeutic purpose in interventional pain management. Aim: We aimed to study the effect of adding dexamedetomidine or fentanyl to levobupivacaine in ultrasound guided supraclavicular brachial plexus block in upper extremity surgeries as regard to onset and duration of sensory and motor block and postoperative pain. Methods and Material: The study was carried out in Tanta University Hospital on 90 patients of 18-60 years old with ASA physical status I/II scheduled for elective surgery of upper hand. Patients were divided into three equal groups. Group A: was given 30 ml of 0.5% levobupivacaine with fentanyl 100 µg. Group B: was given 30 ml of 0.5% levobupivacaine with dexamedetomidine 100 µg. Group C: was given 30 ml of 0.5% levobupivacaine with 1ml normal saline. The following data were measured for each patient: hemodynamic status (HR, MAP), onset of sensory and motor block, and duration of sensory and motor block, visual analogue score (VAS) and incidence of complications. Results: Our results showed that no significant difference between three groups according to  hemodynamic changes, while there was significant prolongation in duration of sensory and motor block, significant decrease in VAS  score in group B compared to group A and C. Conclusions: We concluded that the addition of dexmedetomidine was better than fentanyl when both used as adjuvants to levobupivacaine in ultrasound guided brachial plexus block as demonstrated by prolongation of duration of sensory block, improved quality of postoperative analgesia and provide of desirable sedation