Objective To evaluate the diagnostic accuracy of clinical decision rules and physician judgment for identifying clinically important traumatic brain injuries (TBIs) in children with minor head injuries presenting to the emergency department (ED). Methods We prospectively enrolled children <18 years of age with minor head injury (Glasgow Coma Scale 13 – 15) presenting within 24 hours of their injuries. We assessed the ability of 3 clinical decision rules (CATCH, CHALICE, PECARN) and 2 measures of physician judgment (estimated of <1% risk of TBI, actual CT ordering practice) to predict clinically important TBI, as defined by death from TBI, need for neurosurgery, intubation >24 hours for TBI, or hospital admission >2 nights for TBI. Results Among the 1,009 children, 21 (2%; 95% CI: 1% to 3%) had clinically important TBIs. Only physician practice and PECARN identified all clinically important TBIs, with ranked sensitivities as follows (95% CI): Physician practice and PECARN each 100% (84% to 100%), physician estimates 95% (76% to 100%), CATCH 91% (70% to 99%), and CHALICE 84% (60% to 97%). Ranked specificities were as follows: CHALICE 85% (82% to 87%), physician estimates 68% (65% to 71%), PECARN 62% (59% to 66%), physician practice 50% (47% to 53%), and CATCH 44% (41% to 47%). Conclusions Of the 5 modalities studied, only physician practice and PECARN identified all clinically important TBIs, with PECARN being slightly more specific. CHALICE was incompletely sensitive but the most specific of all rules. CATCH was incompletely sensitive and had the poorest specificity of all modalities.