BACKGROUND AND OBJECTIVES: A 4-variable abusive head trauma (AHT) clinical prediction rule (CPR) for use in the PICU was derived and validated for children <3 years of age by the Pediatric Brain Injury Research Network (PediBIRN). We aimed to externally validate PediBIRN as designed (PICU only) as well as using broader inclusion criteria (admitted children with head injuries). METHODS: This was a secondary analysis of a prospective multicenter study of pediatric head injuries at 5 Australian and New Zealand tertiary pediatric centers. Possible AHT was identified by clinician suspicion, epidemiology codes, or a high-risk group (<3 years of age, admitted, abnormal neuroimaging results). At 1 center, we additionally reviewed head injuries in the forensic database. We designated patients as positive for AHT, negative for AHT, or having indeterminate outcome after multidisciplinary review and applied the PediBIRN CPR, blinded to outcome, to PICU admissions only, and any head injury admissions. CPR accuracy was calculated by using 95% confidence intervals. RESULTS: One hundred and forty-one patients were admitted with abnormal neuroimaging results. Twenty-eight (20%) were positive for AHT, 94 (67%) were negative for AHT, and 19 (13%) had indeterminate outcome. Excluding indeterminate cases, in the PICU (n = 28), the CPR was 100% (75%-100%) sensitive and 11% (0%-48%) specific; in all admitted patients (n = 141), sensitivity was 96% (82%-100%) and specificity of 43% (32%-53%). CONCLUSIONS: This validation revealed high sensitivity and low specificity for PICU patients. Specificity was improved but moderate in a broader group of admitted head injury patients.