Little is known regarding the cerebral autoregulation in pediatric traumatic brain injury (TBI). We examined the relationship between cerebral hemodynamic predictors, including cerebral autoregulation, and long-term outcome after severe pediatric TBI. After Institutional Review Board (IRB) approval, a retrospective analysis of prospectively collected data (May 2002 to October 2007) for children age < or =16 years with severe TBI (admission Glasgow Coma Scale [GCS] score <9) was performed. Cerebral autoregulation was assessed within 72 h after TBI. Cerebral hemodynamic predictors (intracranial pressure [ICP], systolic blood pressure [SBP], and cerebral perfusion pressure [CPP]) through the first 72 h after TBI were abstracted. Univariate and multivariate analyses examined the relationship between impaired cerebral autoregulation (autoregulatory index <0.4), intracranial hypertension (ICP >20 mm Hg), and hypotension (SBP <5th percentile and CPP <40 mm Hg). Six-month Glasgow Outcome Scale (GOS) score of <4 defined poor outcome. Ten (28%) of the 36 children examined (9.1 +/- 5.3 [0.8-16] years; 74% male) had poor outcome. Univariate factors associated with poor outcome were impaired cerebral autoregulation (p = 0.005), SBP <5(th) percentile for age and gender (p = 0.02), and low middle cerebral artery flow velocity (<2 SD for age and gender; p = 0.04). Independent risk factors for poor 6-month GOS were impaired cerebral autoregulation (adjusted odds ratio [aOR] 12.0; 95% confidence interval [CI] 1.4-99.4) and hypotension (SBP <5th percentile; aOR 8.8; 95% CI 1.1-70.5), respectively. Previous studies of TBI describing poor outcome with hemodynamics did not consider the status of cerebral autoregulation. In this study, both impaired cerebral autoregulation and SBP <5th percentile were independent risk factors for poor 6-month GOS.