50 adult patients scheduled for percutaneous nephrolithotomy in Sohag university hospitals will be devided in two groups one of them will receive Sonographic guided erector spinae plane block using 20 ml volume of bupivacaine 0.25 percent and the other will receive conventional analgesia of 0.1 mg/kg IV morphine

Inclusion Criteria:

• ASA 1 to ASA 2 18 to 60 years

Exclusion Criteria:

• patient refusal Significant neurological , psychiatric or neuromascular disease Drug abuse Pregnant or lactating women Suspected coagulopathy Morbid obesity Known allergy to some medications Septicaemia and local infection at block site