Aim:To determine the effect of local application of vancomycin powder on surgical site infection rate in patients undergoing instrumented spinal fusion surgeries. Methodolgy:This is a prospective, cohort study which was conducted at SVIMS, a tertiary care hospital. Informed consent was obtained from all the patients recruited in the study. The study conducted during July 2015 to July 2016 with follow up of patients for 1 year post operatively.The study cohort included consecutive patients undergoing posterior spinal fusion for various etiologies. All patients received standard systemic antibiotic prophylaxis consisting of 1 g IV ceftriaxone within 1 hour of surgical incision followed by 1 g IV ceftriaxone every 8 hours for 1 day. All patients underwent preoperative preparation with betadine solution