PURPOSE: Controversy exists regarding whether pediatric blunt abdominal trauma patients with microscopic hematuria should undergo radiographic evaluation. Adult patients have indications such as shock and deceleration injury. This study was conducted to suggest indications for the use of CT to detect significant renal injury in pediatric blunt abdominal trauma patients with microscopic hematuria. METHODS: From January 2005 to December 2009, patients less than 18 years of age with blunt abdominal trauma and microscopic hematuria who had undergone CT were included in this retrospective study. We analyzed the correlation between microscopic hematuria, shock, deceleration injury, and American Association for the Surgery of Trauma (AAST) renal injury grade. Patients were divided into two groups: the insignificant renal injury group (AAST grade 1) and the significant renal injury group (AAST grades 2-5). We compared age, gender, mechanism of injury, degree of microscopic hematuria, evidence of shock, presence of deceleration injury, and associated injuries between the two groups. We analyzed the effect of each of the above each factors on renal injury by using a logistic regression analysis. RESULTS: Forty-three children were included, and the median age was 15 years. Five children had a significant renal injury. No significant differences, except age and microscopic hematuria (more than 30 red blood cells per high power field (RBC/HPF), p = 0.005) existed between the insignificant and the significant injury groups. A positive correlation existed between renal injury and microscopic hematuria (rho = 0.406, p = 0.007), but renal injury was not correlated with shock and deceleration injury. In the multivariate regression analysis, microscopic hematuria was the only factor correlated with renal injury (p = 0.042). CONCLUSION: If a microscopic hematuria of more than 30 RBC/HPF exists, the use of CT should be considerd, regardless of shock and deceleration injury to detect significant renal injury in pediatric blunt abdominal trauma patients.