Objectives: To study the prevalence and the risk factors for surgical site infection in patients who underwent posterior instrumented surgery for thoracolumbar burst fractures. Methodology: Retrospective review of cases operated between year 2006 and 2007. The final end point is the detection of surgical site infection within one year. Results: A total of 38 cases were reviewed. Surgical site infection occurred in 5 cases. Only one had deep infection. The onset of infection occurred within one month in all cases. The risk factors studied were smoking, timing of surgery, duration of surgery, neurological deficit, associated injuries and high dose methylprednisolone administration. None of them were statistically significant as risk factors for surgical site infection. Conclusion: The prevalence of surgical site infection in patients who underwent posterior instrumented surgery for thoracolumbar burst fractures was 13%.