OBJECTIVESAlthough closed head injuries occur commonly in children, most do not have a clinically important traumatic brain injury (ciTBI) and do not require neuroimaging. We sought to determine whether the utilization of computed tomography of the head (CT-H) in children presenting to an emergency department (ED) with a closed head injury changed after publication of validated clinical prediction rules to identify children at risk of ciTBI by the Pediatric Emergency Care Applied Research Network (PECARN). METHODSWe used the nationwide ED sample (2008–2013) to examine children visiting an ED after a mild closed head injury. Multiple patient and hospital characteristics were assessed. RESULTSOf the 4,552,071 children presenting to an ED with a mild closed head injury, 1,181,659 (26.0%) underwent CT-H. Care was most commonly received at metropolitan teaching hospitals (43.5%) and varied markedly by geographic region. Overall, there were no significant changes in the nationwide rates of CT-H utilization in the period immediately after publication of the PECARN prediction rules. However, compared with metropolitan teaching hospitals, CT-H utilization increased significantly for patients treated at nonteaching hospitals and at nonmetropolitan hospitals. CONCLUSIONSThere was no overall reduction in CT-H utilization after publication of the 2009 PECARN prediction rules. However, patients treated at metropolitan teaching hospitals were significantly less likely to undergo CT-H after 2009, suggesting some penetration of the PECARN tool in that setting. Further research should study patterns of CT-H utilization in nonteaching hospitals and nonmetropolitan hospitals to assess challenges for adoption of validated pediatric ciTBI prediction rules.