Acute pain management in open nephrectomy is a challenging issue, due to large subcostal flank incision that is generally employed to have a wide operative field but, it requires considerable amount of muscle cutting giving rise to somatic pain transmitted through intercostal nerves at T9-T11. In addition, visceral pain is also a component of postoperative pain which is transmitted through sympathetic fibers T8-T12 spinal segments. There are limited studies on erector spinae plane block being used for pain relief in patients undergoing open nephrectomy, hence we propose to study the analgesic efficacy of erector spinae plane block vs wound site infiltration in open nephrectomy surgeries. A randomized observational study will be conducted in ASA I-III patients, aged 18-75 years, of either sex, undergoing open nephrectomy with flank incision under general anesthesia with endotracheal intubation.These patients will be randomly allocated into 2 groups, one group will receive ultrasound guided erector spinae plane block with 30 ml of 0.2% ropivacaine after the induction of general anesthesia and second group will receive  local infiltration of 30 ml of 0.2% ropivacaine (LIA) along the line of skin incision at the end of surgery. Duration of pain relief and  Visual Analogue scale (VAS) scores for pain will be recorded as primary outcome measures, with quality of recovery score (QoR-15) and cumulative amount of rescue analgesia needed, as secondary outcome variables.