Objective To evaluate the association between neuromuscular blocking agents (NMBA) and outcome, intracranial pressure (ICP) and medical complications in children with severe TBI. Design A secondary analysis of a randomized, controlled trial of therapeutic hypothermia. Setting 17 hospitals in US, Australia, and New Zealand Patients Children (< 18 y) with severe TBI. Interventions None for this secondary analysis. Measurements and Main Results Children received NMBA on the majority of days of the study (69.6%) and the modified Pediatric Intensity Level of Therapy (mPILOT) scores (modified by removing NMBA administration from the score) were increased on days when NMBA were used (9.67 ± 0.21 vs. 5.48 ± 0.26, p < 0.001). Children were stratified into groups based on exposure to NMBA (Group 1 received NMBA each study day; Group 2 did not). Group 1 had increased number of daily ICP readings > 20 mmHg (4.4 ± 1.1 v. 2.4 ± 0.5, p = 0.015) and longer ICU length of stay (LOS) and hospital length of stay (p = 0.003 and 0.07, respectively, Kaplan-Meier). The Glasgow Outcome Score – Extended for Pediatrics at hospital discharge, 3 mo, 6 mo and 12 mo after TBI and medical complications observed during the acute hospitalization were similar between groups. Conclusions Administration of NMBA was ubiquitous and daily administration of NMBA was associated with intracranial hypertension but not outcomes – likely indicating that increased injury severity prompted their use. Despite this, NMBA use was not associated with complications. A different study design – perhaps using randomization or methodologies – of a larger cohort will be required to determine if NMBA use is helpful after severe TBI in children.