Renal trauma grading is often classified by the criteria of American Association for the Surgery of Trauma (AAST) renal injury scale. Clinically grade I to grade III renal injury can be managed conservatively, and grade V renal injury needs immediate operation. However, the management of grade IV renal injury remains controversial. In this article we attempt to answer this question through the process of evidence-based medicine and to investigate the management of grade IV renal injury.