To identify the physiological and anatomic factors that characterize the need for operative management of blunt pediatric liver injuries, the case records of 106 pediatric trauma victims with liver injuries over a 6-year period were reviewed. Sixty-nine patients were managed without operation (nonoperative) and 37 underwent operation, 7 with penetrating and 30 with blunt liver injuries. Of these 30 patients, 21 underwent laparotomy due to blunt liver injuries (operative); the remaining 9 patients required operation due to associated intraabdominal injuries. Nine (45%) of the 21 operative patients had major hepatic vein or retrohepatic vena caval injuries, 7 of whom died. Overall mortality was 9.4% (10/106). When nonoperative and operative groups were compared, those who underwent laparotomy due to blunt liver injuries: (1) had significantly lower Champion and Pediatric Trauma Scores due to multisystem injury; (2) had 25% or greater lobar disruption with pelvic blood collections on computed tomography scan; (3) underwent early transfusion within 2 hours of admission (18/21); and (4) were frequently found to have a major hepatic vein or retrohepatic vena caval injury at the time of operation. Only one patient successfully managed without operation received greater than 30 mL/kg of blood products within 24 hours of admission. As selective nonoperative management of pediatric liver injuries gains widespread acceptance, the identification of factors that predict the need for operative intervention will limit the potential risks of delay in treatment.