IMPORTANCE Compliance with evidence-based guidelines in traumatic brain injury (TBI) has been proposed as a marker of hospital quality. However, the association between hospital-level compliance rates and risk-adjusted clinical outcomes for patients with TBI remains poorly understood. OBJECTIVE To examine whether hospital-level compliance with the Brain Trauma Foundation guidelines for intracranial pressure monitoring and craniotomy is associated with risk-adjusted mortality rates for patients with severe TBI. DESIGN, SETTING, AND PARTICIPANTS All adult patients (N = 734) who presented to a regional consortium of 14 hospitals from January 1, 2009, through December 31, 2010, with severe TBI (ie, blunt head trauma, Glasgow Coma Scale score of <9, and abnormal intracranial findings from computed tomography of the head). Data analysis took place from December 2013 through January 2015. We used hierarchical mixed-effects models to assess the association between hospital-level compliance with Brain Trauma Foundation guidelines and mortality rates after adjusting for patient-level demographics, severity of trauma (eg, mechanism of injury and Injury Severity Score), and TBI-specific variables (eg, cranial nerve reflexes and findings from computed tomography of the head). MAINOUTCOMESAND MEASURES Hospital-level risk-adjusted inpatient mortality rate and hospital-level compliance with Brain Trauma Foundation guidelines for intracranial pressure monitoring and craniotomy. RESULTS Unadjusted mortality rates varied by site from 20.0% to 50.0% (median, 42.6; interquartile range, 35.5-46.2); risk-adjusted rates varied from 24.3% to 56.7% (median, 41.1; interquartile range, 36.4-47.8). Overall, only 338 of 734 patients (46.1%) with an appropriate indication underwent placement of an intracranial pressure monitor and only 134 of 335 (45.6%) underwent craniotomy. Hospital-level compliance ranged from 9.6% to 65.2% for intracranial pressure monitoring and 6.7% to 76.2% for craniotomy. Despite widespread variation in compliance across hospitals, we found no association between hospital-level compliance rates and risk-adjusted patient outcomes (Spearman ρ = 0.030 [P = .92] for ICP monitoring and Spearman ρ = -0.066 [P = .83] for craniotomy). CONCLUSIONS AND RELEVANCE Hospital-level compliance with evidence-based guidelines has minimal association with risk-adjusted outcomes in patients with severe TBI. Our results suggest that caution should be taken before using compliance with these measures as independent quality metrics. Given the complexity of TBI care, outcomes-based metrics, including functional recovery, may be more accurate than current process measures at determining hospital quality.