Background: The aim of this trial was to assess the effect of hyaluronidase and MgSo4 when 
added in combination to bupivacaine on the onset of sensory and motor block, quality of 
block and effect on duration of action. Methods: Fourty ASA I, II patients of either sex 
undergoing upper limb Surgery under ultrasound-guided supraclavicular brachial block were 
recruited in this in this prospective randomized double blinded controlled study and bottles 
numbered from 1 to 40 were prepared and divided in to two groups each group containe 20 
bottles. The solutions in these bottles contain 30 ml volume. The first group contains a 
mixture of (28 ml 0.5% bupivacaine and 2 ml 0.9% normal saline). The second group 
contains a (mixture of 28 ml 0.5%bupivacaine and 2 ml of MgSo4 containing 200 mg mixed 
with 1000 unit hyaluronidase). Results: The onset of sensory and motor block was faster in 
group (II) than patients in group (I). Also the duration of sensory and motor block was found 
to be longer in group (II) than in group (I). Conclusions: Our study demonstrates that the 
combination of hyaluronidase and MgSo4 with bupivacaine for supraclavicular block 
decrease the onset for surgical anesthesia and increase the duration of sensory block thus it 
decrease analgesic requirments without significant complications.